(I figured the link out)
Take a look at this review which includes all three of those monitors:
http://www.desktoppipeline.com/showArticle.jhtml?articleID=175003542&pgno=6
Heck, they all sound pretty good, but from my interpretation of it, the VP2130b seemed to win for response with the NEC slowly behind. From the other Maximum PC review I read, the Samsung was slow. It's hard to know who to trust but given previous trends the VP2130b is probably the best overall since it's fast and had reasonably good image results. They actually all use the same 8 ms (g2g) S-PVA (Samsung LTM213U6) panel, although ViewSonic may have tweaked it to be faster. The NEC had a steep price and I'm not sure it's worth it.
If gaming was a priority I'd stick with the ViewSonic because of that Max PC review, and also because ViewSonic has the fastest monitors on the market these days. The Samsung may edge it out in image quality, although even that is debateable because both use a Samsung S-PVA panel. The Samsungs only had an edge when the competitors used slightly lower-contrast P-MVA panels as far as I know.
If you want to be sure, you could stick with the trusty 20.1" ViewSonic VP2030b (P-MVA), though smaller, it has a finer dot pitch and the same resolution as the 21" monitors. Even then, you may prefer the Samsung 204b (TN) for gaming since TN panels are always overall faster (difference is negligible where the MVA is faster, but the TN is a lot faster than the MVA in some transitions).
You can see comparisons of those two here:
http://www.lesnumeriques.com/duels.php?...01&p1=1021&ma2=41&mo2=108&p2=1073&ph=1
Choose under "Etape 3" for different test scenarios. It's generally easy to tell what's going on in the tests. For the color bar ones, lower is better (it has a lower delta from the requested color).