I really don't believe your 9550 (I have a 9600) works perfectly with compiz (without firefox or other programs scrolling problems), I don't believe it works well with aiglx like xgl and I don't believe you can watch films without flickering USING OPENGL OUTPUT (OR XV, I don't remember which between them works).
and last: why do you want to force your board to run compiz?! it's just too much for those boards. even if you have 512mb of vram remember that 9600 is old and on agp (at least i have an agp board). compiz should not be run unless you have an r500, in my opinion. so using that stuff, a part from being totally useless and productive damaging since your eyes will go mad after less than 30 or 40 mins. and then if you also have 7.3 with server 1.4 then you'll have more problems.
there is still a limit to the old hardware. i personally have a pc of 2 years and i'm starting to see some latency problems with the new stuff which is more and more memory consuming. it's true that linux enhances the lifecycle of pcs.
i also personally use a pc of almost 10 years with gentoo 2007 and kde 3.5.8 and various stuff on it, and it still behaves quite well once it starts this amd k6-i 400mhz in overclock to 450 and 256 mbs of ram which makes daily automadet backups, apache/tomcat/php/mysql and also as portage/paludis network mirror, so that i can upgrade multiple pcs with one sync. also it is inserted into the icecream compiling personal cluster and behaves fine. but it will never get to run compiz or beryl even if i get an agp4x 9250 with 256mb or ram, which would probably be enough to run compiz/beryl.
but returning to the point: is you use the latest stuff and compiz (which is still not officially supported and working from the release notes) you'll probably.