4550 is not faster than the 3650... I did a ton of research on this one because I recently found myself with a computer with a low profile case for the first time. I built the pc myself and need a slim tower case. Was using onboard graphics which were aweful so I decided to get a low profile card for gaming.
Did alot of research and as mentioned above at the present time the 9600gt is definitely the best low profile card available. However it was out of my price range (ridiculously tight budget at the moment) and so I had to look for the next quickest card which happened to come in ATI flavors... Which is what you mentioned you were looking for.
I did a ton of research because I initially thought that the 4550 low profile would be much faster than the 3650 but it is actually the other way around.... like big time! The 4550 is at times about half of the speed of the 3650. Newegg no longer sells the 3650 low profile (stopped selling it like a day before i decided to buy it lol..) So I had to google another vendor in order to buy the card.
I know the card says minimum spec of 300 watt power supply but I am running it without a hitch on a 275 watt supply right now. Of course I have an Athlon X2 5200 which is only pulling 65 watts, only one hard drive, one dvd burner, and two case fans pulling power. If you have another hardrive or a processor which is pulling more juice the minimum power requirement might apply... That was my issue with the 9600GT as well because it required a minimum of 400watts i believe and I definitly didn't have the $$$ to upgrade my PSU as well.
Anyhow I got a Sapphire Low profile ATI HD 3650 512 meg video card and it kicks butt for how cheap it was. This is the fastest low profile ATI card you can purchase at the moment (if you can find it). DO NOT GET THE 4550, it's big fault is it only has a 64-bit memory bus as opposed to a 128 bit bus in the 3650, THIS MAKES A SIGNIFICANT DIFFERENCE IN PERFORMANCE between the two. So get the 3650 or hold out for a while and see if they make a low profile 4650 with a 128 bit bus if you must get an ATI card.
Tom's hardward btw has a beautiful breakdown on all of the graphics cards which are currently offered (almost up to date). The 3650 is about half speed of what a low profile 9600gt is though, so if you can get NVIDIA and you have the PSU to support it, that is definitely the fastest low profile solution. But if you are stuck ATI get the 3650...
PS - it also has HDMI out, but I haven't messed with that so I can't tell you how well it works...
Just for some ideas on Games, i haven't checked the framerate but I game at 1440x900 and Bioshock runs smoothly in DX9 mode (unstable in DX10 but that is the fault of the crappy game programming not the card...) at max settings.
Also I run Overlord: Raising Hell which is fairly graphically intense and it runs pretty smoothly maxed out at that resolution.
I am also a big fan of Oblivion and I have been EXTREMELY pleased with it. Max Settings at that resuloion with 16x Anisotropic Filtering turned on in ATI control panel (makes the textures look gorgeous) and HDR turned on in game (graphics card intensive specs) however no anti-aliasing. All Draw and View distances set to MAX. All that to say the game looks amazing, especially with HDR turned on and runs fairly smoothly (small hiccups every now and then, hardly noticable and i think I just need to tweak the game a bit and it's not actually the graphics card causing the hiccups).
I have been very please, I am not expecting to whip Crysis out on this or anything but as far as last generation games go, this card does a pretty awesome job. The 9600gt is still twice as quick, but if you must go low-profile ATI, at the moment nothing is faster than a 3650...
Here is a decent benchmark showing some of the differences i talked about above...
http://www.pcgameshardware.com..._4550_reviewed/?page=6