mouse24 :
Yeah it will work fine, the 5450 only uses 10w. Its not a gaming card by any means, I doubt its much better than your ondie GPU. Though that PSU disgusts me, it can only output 240w max...
I think you mean can only output 240 watts @ 12 volts.
More like that power supply is very old(design wise).
Before some of the more power hungry components came along, power supplies used to actually use a fair bit more 3.3 and 5 than they do now.
The reason for the switch to 12 volts was simple. Smaller traces and wires allow more wattage at higher voltage. It is all still dropped to the sub 2 volts required with in the voltage regulation module of the device it powers.
As example running a GTX 680(195 watt) would be 39 amps @ 5 volts(requires larger wire) and 59 amps @ 3.3 volts(requires much larger wire) while it is a a much more friendly 16.25 amps @ 12 volts.
Even quality power supplies like the Antec Truepower series of the day had what would seem like rather low 12 volt capacity by todays standards.
Modern designs also differ in the fact that older designs have a fully dedicated setup for the rails, while modern ones will generate massive amounts of 12 volt current and then use DC-DC converters(little dc switching power supplies) to generate the 5 and 3.3 volt lines.
This means that if you actually max out the 3.3 and 5 volt lines one a modern power supply, the 12 volt capacity will in fact go down from what is listed(thus a MAX combined for 3.3/5/12 is listed). Now with most parts running off the 12 volt rail this is not much of an issue and this design allows older hardware to still work fine with the newer supplies.
As for the card, it will work without issues,. As other have said, it is NOT a gaming card as it is more built around media playback duties.
Sorry for the rather late reply, got side tracked before submitting