Help Needed!! 64-bit and GDDR3 or 128-bit DDR2?

I am torn between two budget graphics cards for my system and would welcome some advice on which would be best. One is the Sapphire Radeon HD 4550 and the other is the EVGA GeForce 9500 GT. The main differences between the versions I am considering is that one is 512MB 64-bit GDDR3, while the other is 512 MB 128-bit DDR2. EVGA also recommends a minimum 350 watt power supply, whereas a 300 watt PSU is recommended for the 4550. My system is an Acer M5100 with 5000+ AMD Athlon 64X2 dual core processor with 2 GB DDR2 memory and 500 GB hard drive, running Vista 32-bit. It only has a 300 watt power supply with (I think) 22A on the +12V rails (see below).

I am planning to use the system primarily for high-definition DVD viewing and maybe some occassional light gaming. These cards push my budget, so I can't really afford to step up to anything more pricey.

Thanks in advance.

HD 4550 methinks. Lower power requirement, and ATi does great multimedia.

With power play support,unified decoder,7.1 HDMI audio extremely low power usage its just to hard to turn down ATI.