Yeah, that solves the video card issue then. and would be great for games
As for the AMD CPU, there are two main things to look for, the speed, and the manufacturing name.
The speeds are different to Intel Pentiums, which you might know. Even though a 3000+ AMD processor only runs at 2.8GHZ, its still as fast, or hence the plus, a bit faster than a 3.0ghz Pentium CPU, and this would do your system fine with good RAM and Video card to boot.
The CPU type, or core is another. The first one they released in the 64bit range was the ClawHammer, and then the Winchester, followed by the Venice (the newer one which improves more on the Winchester core, including a 90nm manufacturing process, means for a cooler CPU like the Winchester had. The improvements are more towards memory type things)
Now, it also matters what type of AMD system you want. AMD 64 is of course the newest type, and you should aim for it. Basically it has the capability to run 64bit processes, so when a Windows 64bit is released (as it is now) and programs start using the 64bit process, you'll gain a improvement straight away, rather than people with older AMD XP processors which will have to update to use them
You saying RAM and Mobo not mattering though is not true, as this does matter...alot. If you dont get a good motherboard, the CPU would be slowed down quite considerably, as well as with the RAM.
It is always best to get the fastest RAM available for use with the motherboard that it supports (for example: PC3200/DDR400), and the minimum to get now is 512mb which would be fine for most peoples uses as its become the normal for PC's, though 1gb (would see a difference if you ran a load at once) would also see an improvement in some cases.
I'm sure people here could advise you on makes of motherboard, etc to go for.
I hope this helps