The 9250 is better than 9200, 9250 SE is better than 9200 SE, but 9250 SE is worse than 9200.
The 9550 is worse than both 9500 and 9600, but better than 9600 SE. 9550 SE is worse than 9600 SE, but better than both 9250 and 9250 SE.
Does this clear things up or does it only make you more confused? :lol:
Anyway, if you have space for two brackets and on a tight budget I'd recommend
this one, as it's about the same price as the 9200s and 9250s, but faster and DX9 compliant.
If you wanna spend more you could go for a 9600, but most (all?) low-profile 9600 are the SE version, which are only marginally better than the 9550 SEs that I've recommened and not worth the extra money. It sometimes/often says just '9600' on shops' websites even though they really are 9600 SEs.
Note: SE models have a 64-bit memory bus instead of a 128-bit bus, halving memory speed.