Attached Link: Purchased omputer parts thread

I just purchased the components to build a new dual core system based on an earlier thread people in the Vue forum were so kind to give me advice with

The OS I purchased is a Windows XP Pro 32bit with an upgrade path to Vista Pro 64 bit. The salesperson told me they did not have the Windows XP Pro 32bit in stock and it would take 2 weeks to order it.

  After reading some posts in the Poser forum I am concerned I should have purchased Window XP Pro 64 bit. i can still make the exchange as I have not opened the package yet. I also purchased 4 gigs of Ram. The sales person told me that windows 32bit can only read 3 gigs of ram and will degrade. Any advice on this.

  If I go to XP Pro 64 bit do you know if these software packages will run on it?
Vue Inf 6
Poser 6
Poser 7
Z brush (latest)
Cararra Pro
Photoshop 7 and Photoshop Cs

thanks so much for any advice you care to give me.
I would like to add that I am not a hardware or OS guru so I prefer to take the path that will keep my system and apps running with the least number of problems.