Should I buy a new computer?

[Lefort]

Hello. I'm currently running an eMachine with an AMD Sempron 3100+ 1.8 GHz, 512MB DDR SDRAM, and its lagging when I multi-task. Multi-tasking includes: 6-8 tabling across 1-2 different sites, PAHud, MSN, AIM, mIRC, music, internet browser.

I'm not all that computer savvy, and my intentions were to just go buy a new desktop PC.. but then I realized that I'd want my current HD to be put in the new one as well as the video card which allows me dual monitors. So if thats the case, would I be best to just buy more RAM?

Keep in mind that I'm no good with "installing" new processors and whatnot. My hardware skills are pretty much limited to being able to pop in RAM or a video card.

Thanks