Just from past dealings with this... in fact, IBM too... I found it was FAR cheaper to:
-sell your current laptop on eBay, you can probably get $500 or more (I sold my P1 133MHz a few months back for $200)
-buy a new one
IBMs are very expensive and lack any advantages, in fact, all but their newest have that dumb track point mouse (hate it! lol)
If you want IBM, it's best either to find one on the Web, or find an Employee, as they get a decent discount on them. Otherwise, look on the Web... My sister just got a Sager from eBay, and as far as I know she likes it/hasn't had any problems with it...it was a pretty decent laptop for gaming, for the price. Close to what my desktop is now, and I believe it was ~$1000. Better graphics card though.
So yeah, I strongly suggest a new one if you can.
However...if you want to upgrade...I'm sure you can find those parts on eBay or other websites, just Google them, but I don't think it'd be worth the money you'd be paying.