Going from XP to 7 will be an improvement even if you only have the capacipty to use 4gb of ram.

XP 32bit will use somewhere near 4gb, but ir doesnt manage it very well due to 32 bit restrictions.  & 64bit has a much improved memory management system.

Besides, when you do upgrade your mobo in the future you will be all set up and ready with your 64bit os :)

If I can recommend a card it would be a geforce 240gt.  An excellent and inexpensive card with 1gb of dedicated ram.  But in all honesty any graphics card based on recent(ish) architecture would be good.

I use the gt240 because it has nearly 100 CUDA processors, which I am sure poser does not use, but my beloved 3d coat does :) so it speeds that up nicely.

Whichever card you go for I would plump for the most recent architecture you can afford, the GT240 for example is only a little more expensive than the geforce 9 ranges, but is slightly faster and supports a few more features.  It's just a minor future proofing thing.

Don't listen to IT experts though, that's the first mistake :) unless it's me of course.  But only cos I have 22 years in the business and don't stand to make any comission off ya :)

John

Fugazi (without the aid of a safety net)

https://www.facebook.com/Fugazi3D