Easy way round it like i have done is put 64 and 32 bit on 2 partition's, then dual boot.
Keep every update for XP on couple dvd's as most people dont want vista but stick with xp, and unlike 98 where microsoft floged off cheap ther stocks of 98. 
He will soon destroy all old stocks of XP in microsoft warehouses so i backed up my win 3.0 3.1, 3.11, 95 2 versions, 98 2 versions, and my home and pro and xp64.
2 operationg systems or more on comp better way to go and some 332 bit aplications will run better on 64 but not all.