Be careful! That Sapphire 9550 is 64 BIT which means it is an SE but the SE is not there. Don't tell me Sapphire is misnaming their 9550 line now too? A normal 9550 is 128 bit.
A 9550 is not good enough to run Doom 3 well. At 1024*768 and high you'll probably get 15-20 fps...maybe less. An SE will probably make it totally unplayable at those settings.
It will also have some trouble running HL2 IF you're planning on running the game at DX9 but there is a console command to let you set it at DX8.1. If you want to run HL2 at DX8.1 that card will be fine. I have one PC with a 9200 SE and it gets 32 constant fps running everything high, reflections simple, no AA and trilinear at 1024*768...except in large gunfights of course where it drops to 18 fps.
If you want to play HL2 at DX9 you need a minimum 9600XT for it to run well at everything high and no AA. You will also see a ton of RAM and a competent CPU.
Honestly don't waste your money on a 9550 SE if you want to run HL2 in DX9. Even so, if you want to run HL2 at DX8.1 you could simply buy a 9200 and it should do fine. Nvidia Tis run HL2 at DX8.1 very well too but 9200s are cheaper.
None of those cards including the 9550 SE or 9550 will run Doom 3 well unless you considerable lower the settings.
Truth is that any card under $60 will be garbage and will not run high end games well especially HL2 in "all it's glory" to quote Gabe.