I have an AGP Nvidia Geforce 6200 running just fine on the Dimension 4600.  As a matter of fact, the Geforce 4 MX 420 is the one I took out.  

Oh right. I take it your're based in the UK?

That's the one with an AGP slot? Or something like that.

Would a 512MB work?

The 4600 has an AGP slot for video cards so this is the type of interface you want.  It should be the upper colored slot that is offset to the right from the other white PCI slots with a release lever on it.  My 6200 is a 256mb card, but a 512mb should work fine.  

Hi there

Righty, so there should be a problem with the power supply or the usage of electricity. I have read some cards can take up a bit of power...

The 6200 does not use much power.  It runs fine on the 250 watt power supply.  

Alright then, sounds fine then. You have one, so it should work. :emotion-1:

You can get Radeon 4650 AGP cards now.

Depends on what you are trying to accomplish.

Maintaining Compatability all the way to Windows 7 would require a Radeon HD 2400 series or better.

Club 3D ATI Radeon HD 2400PRO AGP 256MB DDR2 TV/DVI Out, Retail ...

Asus ATI Radeon 3450 HD 600Mhz 512MB AGP 8x DVI Low Profile ...

a much better card would be

Gigabyte ATI Radeon 4650 HD 600Mhz 1GB AGP DVI (GV-R465D2-1GI ...

Compatible with Windows 7

"Compatible with Windows 7" software and devices carry Microsoft’s assurance that these products

have passed tests for compatibility and reliability with 32-bit and 64-bit Windows 7.

Thank you for the links.

I believe the 6200 should be fine. The card is primarily for some old games released years back that couldn't work with the 64mb one.

If I wanted to buy a new windows, probably better off with a new pc.:emotion-8:

The 6200 is DX9- and Windows 7-compatible.

I installed Windows 7 on a 2350, a lesser machine than yours.