RAM issue?

[thirdxstrike]

{Sorry I didn't get back around to the other post...My computer just stopped doing anything all together, so we formatted... }

Okay, my issue...I have 768 MB of RAM on this computer now, and when somebody's not online, we're playing games. I play my Sims 2, mostly. But after about half an hour of playing, I have to exit and restart the computer. My little light stops flashing and the game acts as if it's only using about 64 MB/RAM. It's so choppy, I can't do anything with it. And with my internet (really only on mine and my moms' users (we're the main users, Dad's never on and my brother uses mine or moms' if he gets on after us))...I swear, as soon as I log on and open up my internet (still with AOL ...still with dial-up, but I KNOW that's not the problem... ), the light goes off, it's slow (again, like it has no RAM,)...It's just a big annoyance. When it gets too bad, I run spyware scanners and virus scanners, but it doesn't really help...At least not for long. I found that keeping Task Manager up and in the taskbar helps kind of...But I still get a very delayed, slow, less than what this computer could do response. Also, I can't just switch users because I get NO RAM that way. I have to restart and log on to my own user, open up Task Manager...And when I play my Sims, I have to close EVERY PROGRAM except Task Manager and Explorer for it to run right! Sometimes I have to close out BigFix or Quick Time (neither of the two are anything I actually use) to clear up even a smidgen of space to let my internet run! UUUUGH!

I don't know, I just have a strange feeling this thing could preform better! Any ideas?