Vaio FW290 for Music Recoding. Vista 64 to 32 Question? Protools. NEED HELP???

Im thinkin about buyin the Sony FW series. Here is some questions. I need some answers if there is guys on here that know a lot about computers.

should i invest in p8400 vs p8600?? im gona be doing heavy recording. recording big wav files.. converting 24 bit files to 16 bit audio to print on cd. should p8400 should able to handle the job?? or should i just spend extra and get p8600

2nd quesiton. for music recording digidesign protools are not compitable with vista 64. here is the thing. the computer i wana buy. its $250 more on a sony site directly. but if i buy it from a 3rd party i get the discount but the problem is that its pre-configured w/ vista 64.

is it possible? to completely wipe the vista 64 and load the windows vista 32 bit premium? am i gona run into problems with drivers? is the pre-configured system gona have different driver software uploads?

i seen on sony site that they offer 32 bit vista business. but if i buy from the directly then its costin me a lot.

is it better to invest into 5400rpm drive vs 7200 rpm drive? do 5400 last longer? whats the major difference. am i gona get more of a performance outta 7200.. i want longevity plus performance.

 

anyone?????