Well I am a bit of a computer geek, so what I would do is build my own, definetly. I have owned two Gateway's, and haven't had any problems. I am currently using a Gateway, and my biggest regret is that I didn't build one myself instead. I will try to give you some advice that will be of use whatever you decide to do.
I would say go for Windows XP, it is the best version of Windows I have seen so far. Basically it is the same as Windows 2000, but with a simplified way of changing settings etc. which would be good for you if you don't know to much about them. It is very stable and all but eliminates crashes and that old blue screen of death.
Now if you are going to go with Windows XP, and you really don't have much of an option unless you want to go Mac or Linux, you absolutely MUST have 256 megs of ram. 512 would be even better, it is what I have and has been working just fine, but if you can afford more get it. Yes Windows is a HUGE memory hog, my machine uses about 200 meg with only Windows running. If you want to be able to work with multiple programs without and hang time you need sufficient memory to hold all of them. That means realistically at least 512.
As for the HD, well I usually go abit smaller than most people would. I would rather spend the extra money on RAM. If you will be doing mostly work, and are not working with graphics, movies or music, then it would be hard to fill a 40gig drive. I also tend to think that having an overly large drive tends to make you keep more junk on that drive. As the drive gets filled it will slow down your computer more. I have a 40gig drive, and have been using it for almost four years now. I installed multiple games, downloaded music and pictures. I also store all of my school assignments, and various other programs that I use. I also have a fair share of junk that I put on, used once or twice and never bothered again. That said I have just reached about 50% full.
Video and sound depend greatly on what you plan to be doing as far as entertainment. If you mean just surfing the web then any cheap sound and video cards would do just fine. I wouldn't recommend using something that comes built in as a part of the motherboard. It steals performance from your computer, that you could be using to do something more useful, even when not playing games. If you want to get into gaming , well then the sky is the limit. You can go and get the most recent cards and spend tons of money. Generally the best value is something that has been around for a while, and has just been passed over by the latest and greatest. You can get cards that will perform just fine for gaming and movies for under $100. Unless you are a PC gaming junkie that will be more than you need.
I doubt you could get a prebuilt PC without a NIC, or network card, but whatever you do make sure you have a NIC. They are not that expensive and are commonly used for broadband service. Also don't forgo on the old 56k modem just because you have plans to get DSL. It is another item that is cheap and you never know when it may come in handy. Another tren with pre-built PCs is to give no floppy drive. I don't really like this, as the floppy is still a real convinient way to store data and transfer between two PCs. Sure Zip disks and CDs are faster and hold more, but not every PC will have a zip drive, and not every PC will have a CDR. Also you can't overwrite on CDR, and they are more expensive than the old standby floppy drive. If you are comfortable you could even just take the one out of your old computer and put it into the new one. I still find myself using my floppy drive on rare occasions, even though I have CDR and Zip drives. Also get a CD-R/RW drive as they are the best for backingup your data. I would say a DVD drive isn't really necessary, I have one but never use it. Zip drives are nice if you can afford them, but the disks are pricey. Also if you work on more than one computer they aren't that common.
I just got an LCD monitor and love it. They are expensive though, and not at all necessary for normal usage. I just got one because somehow a knife ended up stuck in my CRT
. LCD's are nice, and save a ton of desktop space, but they are expensive. It is really just a question of how much you have to spend. If your budget is kind of tight then just get a CRT, it will serve you well. Having a top of the line monitor and crummy computer isn't worth much.
As for the processor, well any modern processor will be fine really. Obviously the faster it is the better, and the longer before it is obsolete. No need to go for the fastest one, bet you couldn't even really tell the difference. If you are budget concious AMD offers good bang for the buck, and they are every bit as reliable as a Pentium. Although if you are buying from Dell you are limited in your options.
As for peripherals, I will say there are a couple of things to get n matter waht. I would say an optical mouse is a must, and get one with a scroll wheel and back / forward buttons. You will never want to go back, it makes navigating the web so easy and faster too. As it is optical it will never get dirty or need cleaning, and it will always move smoothly and precisely. I would also say go for a laser printer. A black and white can be had for under $200, and is just 100 times better than those inkjets. I did the inkjet thing and just got so fed up with them. The ink clogs, runs out at the worst possible momment, and is so expensive to buy. Then after all that all you get is an okay quality color image. I print almost exclusively in B&W anyway, as I also am mostly just doing school work or other work. If I do print a web page or somehting for reference I don't need the color. Color is nice, but not a necessity as far as I am concerned.
Told you I was a bit of a computer geek!
Okay, a HUGE computer geek.
HTH
It's not difficult, there are numerous websites that can guide you through it. I'll second the recommendation of newegg.com if you decide to go that route. I'll elaborate on some good stuff to look for later, when I have a bit more time.
