Can anyone help

Ive recently put together a new pc and started with a fresh install of xp pro sp2, transferred all the hardware over from old pc to the new one and re installed all the software I had on old one over as well.

Everything runs sweet, the audio I record (vocals etc…) sound great.
but the one really annoying thing I have noticed is that the vst instruments do not sound as open or lively/big as they did in old pc? They kinda lack depth and the quality they had in old pc.

Anyone had this happen? Or if anyone can suggest possible causes?

These are my basic specs:

Rme FF800/lacie pci fw800 card, steinberg midex 8, Uad 1,
emu 4040 pci card (proteus x)

Nuendo 3, halion 3, Korg legacy, hypersonic v1.

Old pc

Xp pro sp2
P4 cpu 3 mhz
Asus P4P800-X with intel 865pe chipset fsb 800mhz
4gb ddr 400hz Ram
standard Graphics card on a vga slot

New Pc

Xp Pro Sp2
Q6600 Quad core 2.4mhz
Asus P5QL SE with intel P43 chipset fsb 1066mhz
2gb ddr2 800hz
GeForce 7200 GS 256MB GDDR2 PCI-E