performance and hardware problems abound

hey all,

I currently own a iBook G4 1.33 GHz with 1.25GB of RAM and a 60GB hard drive. I bought it from someone on these forums last October, at which point it was 3 months old. Since the beginning of 2006 (I believe it has only been since then), I have had 7 documented hardware problems with this computer, mostly failed hard drives - even when brand new. I just got my computer back from my university tech support people yesterday with another new hard drive (the 4th or 5th) and a new system board (because it was decided it might be something else causing the hard drives to fail obviously). I have been using it for 24 hours, but increasingly I can't seem to use Safari like I did when I first bought it. If I open several tabs in Safari (like 12), I start getting the beachball after almost every operation I do - closing a tab, typing something in a text field, clicking a link. It took me 20 minutes to do something that should realistically take me 5 or less (even on a PC!). I couldn't take it anymore and I opened up Activity Monitor to see what was taking up so much memory...but now I can't open up Activity Monitor. Either way I try to, through Quicksilver or from the Utilities folder, it pops into the dock and then immediate shrinks away.

I'm using a brand new hard drive with OSX newly installed, a whole new user Library (all my prefs gone unfortunately), a new system board, and 1.25 GBs of RAM for crying out loud. My old Powerbook G4 (12in 768MB of RAM) didn't ever give me this much trouble, even after falling off a moving car and surviving!

The last 3 times I've had to send it to Apple or bring it to the tech support here, it was because while using it all of the sudden everything on the system would freeze and after 30 minutes of nothing changing, there was no choice but to shut down (this happened 3 or 4 times). Upon powering back up, the computer would be unable to find OSX and either give me a blank screen or a Finder icon/question mark screen. Each time I had to have data rescued and a new hard drive installed.

The tech support people told me that if something goes wrong again I should complain to Apple about having a lemon. I don't want to go 2 weeks without a computer again (like I said, I've doen this 7 times in the last 5 months), so barring that possibility, what do I do? How come Activity Monitor no longer opens? How come I can barely use Safari without waiting for the beachball after every move, even with all the RAM I have?

Any help would be seriously appreciated, thank you.