Well are you only looking to play games?
Take into consideration that a top of the line Geforce 3 video card is the same price as a PS2.
If you processor isn’t up to par, add in another $150+ depending on how fast you want to go. More RAM $50+. What kind of hard drive do you have? 20GB should be the bare minimum for a gaming system. Make sure you at least have an ATA66 hard drive. ATA100 is better, but your motherboard has to support it.
Post you computer system specs so we can better help you make a decision. I have a decent computer setup for games, and a PS2. Sometimes it’s really nice to just pop in a game, turn on the TV and stereo, and play. You don’t have to deal with Windows crashing, patches, hang ups, bugs etc.
As far as seeing the PS2 in action, the graphics are beautiful. Most games run at 30 or 60 FSP with no slowdowns. It doubles as a DVD player, had optical digital out for your 5.1 receiver. If you have a stereo hooked to your TV games really come alive. I don’t think you would be disappointed with it.