You don't know what you're talking about, that card can run circles around anything that's in the PS3/360. Its' one of the newest of the ATI cards and should be more than powerful enough to max the game, or at the very least set it to High. I have an 8800GT that can run Fallout 3 at a resolution of 1920 x 1200 and his card will easily out perform mine.
Are you sure you read his card correctly?
"ATI Readon HD 5450"
From Tom's Hardware, his card's tier:
Discrete: 6600 GT, 6800LE, 6800 XT, 7300 GT (DDR2), 8500 GT, 9400 GT
Go (mobile): 7600 (128-bit)
Discrete: 9800 XT, X700 PRO, X800 GT, X800 SE, X1300 XT, X1600 PRO, HD 2400 XT, HD 4350, HD 4550, HD 5450
The PS3's GPU is 4 tiers on Tom's Hardware's chart above his, and yours is an additional four tiers! According to Tom's Hardware his card is some EIGHT tiers below yours on their chart, with three tiers on their chart representing a significant leap in power.
You have to remember that just because the generation of the card is high, the following numbers are the important part. It may be a newer generation card, but it's a very low end one!
Check this out. Your card vs. his:
http://www.hwcompare.com/458/geforce-8800-gt-512mb-vs-radeon-hd-5450/
Now the 8500GT could run Oblivion with graphics turned down... but his card is WAY WAY WAY less powerful than yours, and less powerful than the console hardware.
Edit:
I forgot to post this, here's the Tom's Hardware chart:
http://www.tomshardware.com/reviews/best-graphics-card-game-performance-radeon-hd-6670,2935-7.html