TV Resolution sucks!!

I was planning on using my TV as a monitor for my computer.

it's a 27" RCA "X-Box Ready" not flat screen.

In WinXP Pro i can only have 800x600 resolution with my card on the TV. What makes the resolution, the card it self? or is it the TV.

Can i tweak this?

the Card is an AOpen GeForce TI 200. is upgrading my video card going to fix this i.e. will another company or another chipset like Ti 4600 or 9700 Pro, or even the FX is going to be better for TV Support?

the only way i can see a clear desktop is if I make it at least 135% bigger the the current desktop.(BIG LETTERS).

Thats the TV bro. your gonna need a fancy new TV for higher rez's.