I presume its a AGP card you are looking for. The 6200 is a poor card by modern standards, the 6600GT is far superior. You might also consider a 7600GS as this is meant to be the replacement for the 6600GT and is just slightly better. Theres not a huge difference in it, if the 7600GS is a lot dearer than the 6600GT then just go for the cheaper one, but if its just a couple of quid then go for the 7600GS.
Either will be a vast improvement and you will be happy with them. Regarding the DVI output only this is not a problem as the card should come with a DVI to VGA adaptor and this is just screwed into place. Worth checking but the cards I have seen all included one.
Only word of warning is make sure your power supply is up to it, both cards use a lot of power and have seperate connectors as the AGP slot can't provide enough juice on its own. I have the 7600GS PCI Express card and am very happy with it, good card for the money.