I have another card to throw into the mix.
I have an ageing AGP system. Back in 2008 I managed to get an HD3850 for £100 from Sapphire. Much better performance than the 3650 and certainly good value for money. I fail to see what a 4xxx card would offer that this one couldn't, except HD audio passthrough which isn't even supported for AGP interface.
If you can get this card now, its still a very good DirectX 10 card. Check on Toms Hardware for the ranking as well - still pretty respectable!!!