Weren't we dealing with an almost idential system in another thread?
The CPU is low end. CPU isn't quite so important in gaming anymore, but you'd need a powerful graphics card to take most of the workload so the CPU doesn't have to. Personally I hate the Athlon series because of how much weaker they are compared to any Intel chip.
The graphics "card" (as omgdaniel pointed at) doesn't exist. You're using an Integrated Graphics Processor (IGP), which is the lowest of the low end, from five years ago (the nForce 430 is from 2005). Adding ANY graphics card will greatly improve gaming performance. Naturally, the newer the graphics card, and especially the higher up the scale it is, the better it will perform. Beware though that I don't think your system has PCI-express 2.0, which all modern graphics cards use, so you won't be able to get the full potential out of any modern graphics card without upgrading the motherboard. You can still use them, it just won't go at full speed, but it will still do much better than the IGP you're currently using.
I recommend upgrading pretty much the entire system - the motherboard (and subsequently RAM, although 6GB of DDR2 RAM is still kinda impressive), CPU, Case and the Power Supply Unit (PSU). Of course, that does also depend on your budget, which I get the impression is either low or non-existent. Without more details, that's all I can really say.
Oh, and in everything I said, replace "you" or "your" with "your friend". I'm too lazy to edit all of that to address your friend instead of you
