2ghz of cpu would still suit you fine for windows applications. But for games with a 256mb ram... um... yeah.. it's on the edge.
with about 200 bucks. I would say it's pretty much a waste of money to upgrade on a 2ghz cpu. I would recommend saving up and buying a new one. It could last you maybe 1~2 years, depending on what games you play. I would definitely save up and start all over.
Yes. you can figure out without opening. IF AND ONLY IF
(sounds like a math term, anyways) you know what your Motherboard is . you can just go google and type your motherboard model and it should probably show it to you. If you look at specs, you should see it, or either by just looking at the picture. If there's a slot that looks different from the regular PCI slots, mostly brown colored compared to white pci slots,that means it has an agp slot. Careful, the slot has to be above the pci slots, it's not the ram slots.
tell us what kind of games you play and we could probably get you and good comp at a good price.
I'm not sure about the memory part where it is faster when running 10 windows at a time and such. I'm not really in to the memory stick department so i would need some help on that.