Both harddrives are the at the top of the crop, you can't go wrong with either. If you have the money and want nothing but the best, and you care about brand name, then I guess the IBM is your choice. If you don't care about brand name (even though Maxtor is a great brand IMHO) and would rather save your pennies, the Maxtor is for you.
Aside from the minute (and I do mean MINUTE) differences in performance and price, take into consideration the warranty policy of IBM and Maxtor. I've read of troubles with IBM, where Maxtor seems to replace all drives, OEM or retail, it doesn't matter to them.