|Does the TNT2 have a DVI port? If it does, check your Display settings in Windows - you may have some setting set to something a CRT monitor can do that the DVI monitor can't do.|
If it doesn't have a DVI portn there is no such thing as a card with a single VGA port that can be adapted to a DVI port - it's always the other way around.
I wouldn't go by what one guy says regarding whether a DVI monitor can only be secondary. There's a small possibility that's true, but some people don't know they can switch which monitor is primary or secondary in Display - Settings in Windows. If you really want to find out for sure, look up similar ATI brand name cards on the ATI web site that have the same chipset - ATI specs manuals are often more thourough.
You're not limited to just relatively old ATI chipsets for cards that can use 2X slots - I know for a fact the 9200 and 9550 cards also support 2X, but when you look at info on many clone card websites that isn't clear. Most if not all 9600 cards are 4X/8X only; I believe all 9800 and higher cards can only support 4X/8X or 8X only.
Apollo also has other cards with newer ATI chipsets that definately support 2X. You get the benefits of the newer chipsets, but at 2X speed.
e.g. 9250 64mb (but VGA port only)
9550 64mb (but VGA port only)
This 9200SE probably supports it too, but that isn't specified - you could find out whether it does by looking up cards that have that chipset on the ATI site.
Both DVI and VGA ports:
Some lone card mawers ave better info than others. Sapphire has terrible info. PowerColor might be better.
E.g. here's an ECS card that you might still be able to find as old stock:
(ECS models with a DVI port have a D at the end).
I now nothing about NVidia chipset cards.