http://www.tomshardware.com
http://www.anandtech.com
http://www.cnet.com
Those sites will help you learn about the technology, what's hot and what's not. I'll try to give you the run-down.
- The Pentium 4 architecture with Hyper-Threading technology is about neck-and-neck with modern AMD processors. The P4 itself isn't really a very good choice for anything but a Windows computer, and even then it usually needs special code in the application to get decent speed.
- The Pentium 3 and Pentium-M give far better performance per GHz and are therefore more "overclockable" (if you're into that sort of thing).
- However, overclocking is not really a good idea.
- The Athlon 64-bit processors actually benchmark higher then Pentium 4 for 32-bit processes, especially the latest AMD models. If you must get Pentium and want 64-bit, wait until Intel releases their newer 64-bit models, which have adaptations from technology bought from AMD. They also run cooler then P4s, too.
- For a gaming, a good equation is: CPU 30% + Graphics 50% + RAM 15% + 5% Other . If you upgrade only one of those to the fullest, one of the others will be a bottleneck. Anything else isn't really that big of an issue, that includes the HDD. Note that online games are a little different.
- Good budget video cards are the Nvidia Geforce FX 5900XT and ATI Radeon 9800XT. Any on-board graphics or audio chipset should be avoided for a good computer.
- If you're buying a brand-name computer, don't worry about the RAM. You can save up to $100 buying it yourself.
- Most of anything else not mentioned is hype and will increase your performance to such a relatively small degree that the extra cost isn't worth it. However, if you want to learn about RAID arrays, those are nice for data security.
Maybe I'll think of more later.