that's quite a tough decision then! Unfortunately there haven't been any reviews of the Philips on any of the main sites so we havent seen any direct comparisons with the Belinea or other main models. However, user comments have been very positive. I'd say the build quality is likely to be better on the Philips, since the Belinea has been known to suffer from some backlight leakage since its release. The Philips also offers 1:1 pixel mapping, which the Belinea does not, and so for those games which don't support WS, this might be important. The Belinea offers pretty decent responsiveness for gaming, we have seen quite a lot of reviews of it over at places like BeHardware. User reports of the Philips have been good, but like i say, it's hard to compare the responsiveness without other reviews. I'd say both screens are likely to be quite similar in this regard though. The Philips is probably the more well built and classy of the two, but it might be worth having a read through the massive threads about each one if you do a search.
Can you stretch the budegt at all? If you're looking for a 20"WS gaming screen, the NEC LCD20WGX2 is very highly rated