330 Watt PSU? Should be adequate, unless you have a lot of blinky lights and a stack of HD in your PC.
This question really depends on what kinds of games you play.
PC
Multiplay games
Sophisticated 'I need a keyboard' games
PS/2
Squaresoft and Capcom games?
For the PS2, you won't have to worry about the game not running right or fast enough or with all the eye candy on, and you have PS1 compatibility, plenty of games. It really also depends on the amount of time you spend gaming.
The PS was released in 1991 (?) and there are still games released today that can be run on it. IMHO, I doubt your Radeon would last more than 2 1/2 years. That's also if you don't run into issues installing the card to begin with.
I'd go for the PS2