Windows XP is no longer, Win7 is soon to be replaced as well.
Unless you plan on doing a lot of video rendering, any dual core processor and 4 gig of RAM is more than sufficient. Same with the hard drive, you don't need a huge drive unless you are doing video.
Brand wise, They are all OK.
Bottom line, pick a price point you want to stay at and shop for the most bang for the buck.
"He who knows the way of the worm possesses the power of the fillet knife"..... Capt. Kevin
I would personally steer away from Dell because I just know way too many people who have dealt with power supply issues. I have purchases a lot of Lenovo products in the last few years and feel pretty good about the results. They also have a pretty nice line of laptops to choose from. In case you did not know, Lenovo is basically IBM under another name. They split out their PC business a few years back. As far as laptops their Thinkpad has been a very durable product for many years. Kagee pretty much summed up the rest of what you need to know. For the basic end user nowadays the computers that they are putting out will go well above and beyond what you will need. Just make sure to throw at least 4 GB of memory at it. A new unit should be running 64-bit so you can utilize memory well above the 4 GB whereas with the old 32-bit you were somewhat limited in terms of memory.
you hit it on nose 64 byte will not let lot your XP 32 stuff work on the 64 versions. and I had dual boot my computer to both 64 and 32 as I had lot stuff in 32 versions. to the win 7 last I knew win 8 was to hit the seen in july this year as I beta tested it. man what mess and can not see why to go win 8. win 8 remind me of going to kidder garden. lot blocks thing. I never pay for win 8 and only if that be case to buy new one was standard fare. MS is try rip us on this one more time and dig into our pockets again.
When it comes to fishing "I want results not excuses"
I guess if you do have enough old stuff then having a 32-bit install may be a good option but unless you do the install your self I don't think you will get anything but 64-bit from here on out.
From my experience most old software will still run on 64 bit systems. It obviously depends on the software but I think there many more programs that work than those that will not. If your software employs special device drivers then you may be at a higher risk of incompatibility.
I've been building computers for 18 years or so now.
I'll never own another ATI/AMD product.
If i were you, i would only buy Intel chips and Nvidia graphics. And as always, ram is a huge factor. 4 gig of ram is the very bottom of what you should be looking for. Speed of that ram usually scales with the chip/board as they get newer so whatever is included in a pre-built is usually acceptable as far as ram speed goes.
Thats just the quick and dirty.
Newegg.com has good prices on just about everything electronics. Check slickdeals.net out if your not in a hurry to see if something your interested in pops up.