Ok,

Every time there is a Windows update for XP, it is crashing my machine, which usually results in a fresh HD format.  For some reason, my HP rescue discs wipe the whole HD, and not the windows partition.  After having to re-install everything several times, I've decided to do the following:

1. Add a 1TB SATA HD as a secondary HD and storage for my music Poser, Carrara, and DS stuff.
2. Bump my existing 2GB ram to 4GB.
3. Upgrade to Vista Home Premium 64 bit. 

Here are my Machine stats for my HP a1540n:
AMD Athlon 64 X2 4200 (supports both 32 and 64 bit  platforms)
2 GB PC2-4200 DDR2 SDRAM
250 GB SATA HD

Here are my questions:

1. Will Poser Pro(P7.5 as some refer to it), Carrara 6, and DS work with Vista Home Premium 64 bit, or should I stick with 32 bit?
2. If I have a second HD already installed, will Vista automatically recognize it, or will I need to re-format it?
3. Is this a wise upgrade, or should I save my pennies for a "shiny new machine"?

Thanks,
Starkdog