I have a 32 bit Windows XP computer with 2 gigabytes of Ram.  I know with 32 bit a single application can only use up to 2 gigs of memory.  If I increased my ram to 3 gigabytes would this help Vue, then it could use the entire 2 gigs of memory an Windows can run on the other.  I was also wondering if it would help with the shader tree and repose Poser options, since I'd read that Poser is operating in the background when you use those features (would it run in a separate process, not using Vue's 2 gigs of memory.

I can' really go 64 bit unless I do a dual boot system because some of my hardware doesn't have 64 bit compatible hardware.

You can use upto 4Gbt in 32, but accessible by application under WindowsXP only 3Gbt..
If you run more then one application at time more memore does help. 
And usualy Windows still sneak in to 3 Gbt memory and take some for residential programms.
If you have chose, add memory.

Putting 4GB of RAM into a 32bit machine running XP would be wasted. This little gem was revealed to me by a support colleague. If you go to the computer properties of a machine with 4GB of RAM, you see that only 3.6 GB or so is actually seen. Applications typically will only be given a 2GB virtual address space, although some can be tricked or fooled into working with a 3GB address space. Poser running as a separate process would be given a 2GB virtual address space too, the fun bit is that as memory usage rises, you will find that the machine will page to disk to satisfy demands. My experience with Vue having moved from a 1.5 GB machine to a newer faster 3GB machine is that the extra memory makes no difference in terms of the perennial out of memory and stability issues with Vue. I hit the wall with three or four Poser figures in 1.5 GB of RAM as I do with 3GB. The main benefit I've found with 3GB is being able to work with other applications at the same time, and avoiding the slow paging of virtual memory to and from the disk.