HD 5570 or 6670 as HP Z200 video upgrade

Thought this would be straight forward but HP like to make things difficult don't they? Bought my 14 yr old a HP Z200 workstation at auction ( yes funds are limited) as his first PC. Figured it would do him for 12 months or so and then he can start upgrading as he needs to.

Current specs are:

i5 650 with
2x 1GB (1333 nonbufferred ECC DDR3)
NVIDIA Quadro NVS 295 (256MB)
250GB SATA HDD 1
1000GB SATA HDD 2

running 64bit Windows 7 pro

no optical drives as yet and connected via Netgear USB to home wireless network.

The catch is that the Z200 uses a proprietory 320W PSU so think I might have to be careful in choice of video cards that the PSU will support given that a new mobo and PSU is not in scope just yet.

I'm looking for something that will run Skyrim and the soon to be delivered creation kit well.

Can anyone advise on suitability of the HD5570 or 5670 cards. They seem to be within his budget. bear in mind that he plans to add another 2x 2GB ram in the vacant slots to give a total of 6GB.

Recommendations on other options welcome.

Cheers!

You are correct to be concerned about the 320W PSU. If you limit yourself to any card that does not require an external PCIe power cable, you should be alright. The HD 5x70 cards fit that scenerio. I would go with a 1G HD 5670. It should provide good framerates at 1680x1050 and lower if you don't overdo the 'eye candy'.

Thanks clutchc!

Opened the Z200 today.. didn't realise - its actually got 2x Quadro nvs295s in it.