Why don't you go with what Lotsurb has (except for the SCSI drive)? If there was a problem with component compatability, he would know. Vista has it's problems but it's not all that bad. Definately do not get the 64bit version though. Same goes for XP.
Before you make any purchases, be fairly certain that building a machine is something you thing you can do. It's not for everyone. It takes patience and the willingness to learn something new. It can be a rewarding experience or it can be a nightmare depending on your skill level. Do some research before you decide.
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