Go through
www.transintl.com and call them and talk to Mike or Tony.
Get the Hitachi-IBM 80GB for the largest.
They also have a 7200rpm.
And they have a 60GB Toshiba 4200rpm. Tell 'em to match Googlegear.com at their price of $159 plus free second-day shipping -- they will.
Transinternational is the best group of people you could buy from -- they stand behind their products 100%.
Personally, for the system you have I'd think that the 60GB Toshiba at $159 is a great buy.
Good luck.
Oh, one more thing? Transinternational has directions for installing your drive online at their website also.