The PS2 doesn't output VGA natively, like the Dreamcast does, or the GameCube can be hacked to do. The VGA adapters for it and other consoles (other than Dreamcast, and sometimes GameCube) are upscan converters. Usually they have a circuit that takes the composite or S-video and converts it to digital RGB, which is then sent another circuit that upscans it and outputs analog SVGA.
Each time a signal is converted it looses a little bit of quality. So, a PS2, or other console that needs to be upscaned, will never look as good as a Dreamcast on arcade monitor.
I've never used a Rage Fury Pro AV, so I can't comment on that exact configuration. However, I do have a TView 99 and the quality is about the same as as most converters. On slower computers, Pentiums, the VGA box wins hands down, as it never looses frames, but for PII+ systems a good capture card will be just as good.
If you want the best quality on your PC, use S-video instead of composite into your capture card.