but, the newer iterations of the celeron actually have on die memory making it a better deal than it used to be IMO. I would go with a pentium though myself as they generally have 1Mb of L2 cache as opposed to 256k on the celeron. This allows for faster processing of data per clock cycle (clock cycle measured in mega or gigahertz) than with the celeron.
and might I recommend newegg.com if you plan on purchasing online? they have never done me wrong, have great service and above average pricing. meaning lower than average of course.
if you get a laptop then, imo again, you should go with a pentium-m as opposed to celeron or centrino. the m stands for mobile and is apparently a great, low power consumption processor. additionally, the processor itself is no different from that on the centrino only without the premium added for (on the centrino) intel branded wireless. so, if you want wireless connectivity on the notebook you can usually find the exact same wireless onboard controller in the pentium m models as you find in the centrino- only without the neato brand name and added price.