I did a lot of research on the ATI Radeon 7000.   If you buy a true ATI branded card, the 7000 comes in several different forms.  You can get PCI or AGP, 32 MB or 64 MB, with or w/o S-Video out.  But not a single variant has Video  >IN<.     Non-ATI branded radeon 7000's *might* have video in, dunno.
I ended up buying an ATI Radeon 7000 AGP 64 MB sVideo out, for $70 at Microcenter.  I love it.  But no video in...
Also, I do have another card with S-Video >in< on a Mac.  I've connected the PS2 there, and it looks like crap.    general rule is that Consoles will look better on TV, and PC games better on PC Monitors.   
If you try running a PS2 on a PC monitor, you will see all sorts of little defects...  it looks real bad I tell you!