You'll get official ATI Catalyst, Omega Catalyst and NGO Catalyst.
I really don't know if the two latter ones actually benefit anyone, although this is my own view.
Omega still releases with the old catalyst control panel, and ATi's official one's release with Catalyst Control Center - which can be annoying as you need .Net 1.0/2.0 for it to work, and switching to the interface can sometimes take a few seconds. NGO I never tried.
I'd recon stick to ATi's official drivers, because if you have a XTX you most likely have a up to date rig, so performance (and the few fps optimized NGO/Omega might give you) won't be an issue, plus there's plenty of ways around CCC.... ie ATi Tray Tools or ATiTool
ATT and AtiTool are actually overclocking apps, but in the case of ATiTrayTools, you can adjust AA,AF, monitor temps in graphs, show temps in overlay while yo play games and very important, set fan speed ratios's based on temps.
CCC, must have .Net installed. CCC is just a nice looking interface for setting errr... settings. But, alot of people get the driver only (ATi releases the driver/ccc in one package), and use ATT because you can create profiles which will load AAx4 and AFx8 for game x - this will automatically be done each time the executable is run. So, you rarely need to adjust the settings before launching the game, and it's faster than CCC's profile.
Not going the CCC route, might give you some hic ups with using ATi's transcoding though.
Transcoding, resides in the CCC package, and allows you to code video content from one medium to another (wmv to mpeg4 for example), via the GPU - so it's real quick, up to 5x faster than a CPU can do.
And therein lies the problem - I haven't been able to get the transcoder to work outside the CCC app since the beta of trancoder was out - might be away, but I'm stumped as to how to get it working again.