I would go with the HD4350 (newer tech)
Though according to this: http://www.gpureview.com/show_cards.php?card1=562&card2...
The 3650 will outperform the 4350 in pure FPS but the 4350 probably has better HD decoding and HDCP capabalities.
Also the 4350 draws alot less power and is quieter than the 3650.
I personally have a HD 4650 for my multimedia/office/light gaming tower.
According to that comparison the 3650 is faster but im thinking of the ddr3 HIS 4350 card and how it would compare (not the ddr2 version). see link of card. Power consumption is a plus on the 4350 also. http://www.hisdigital.com/un/product2-498.shtml
If it was mildly overclocked it would help.
The 64-bit memory interface on the 4350 is a drawback.
I went with a Sapphire HD 4650 low profile 1gb PCI-E for my system.
If Newegg is available to you the AGP 4650 is about 60-70 USD.
If you dig around on Ebay you can find OEM cards which have the same specs as the Brand Name but without pretty box and games
I say 4650. The 4xxx on up cards have nice things like flash hardware acceleration. While I do enable hardware acceleration on my 3850 in the backup computer it was hit or miss with older drivers, sometimes it would work while crashing other time. I initially disabled it but with flash defaulting to enabling it with every update, and with some more recent drivers, I just leave it on. Really though, build a new machine