Vegas also used and unfinished version of the U3 engine if I´m correct, still I don´t see UT3 running well on a PC without a dual-core... my buddys PC is a bit better than mine good graphic card and ram and one of the latest non-dual AMDs but Bioshock doesn´t look great at all and UT3 has bigger maps plus more stuff going on.  

Aah well that is a different story, I am not impressed with Oblivion in general graphically. The game looks good, I am not referring to that. What I am saying is the engine requirements are steep for the rewards. I think Oblivion is a bad example of what an efficient and well written engine can do. For instance I have heard several times that Oblivion's culling routines are substandard which when you are utilizing a large outdoors environment can cause quite a performance dip.

To put it simply Oblivion doesn't look as good as Bioshock and yet my system seems to have hiccups on max Oblivion settings in combat but has literally no trouble with max Bioshock settings in combat. The unreal engine 3, and the Cryengine are both much more efficient from what I have seen, but I will admit I don't have a lot to go on other than comparing results from playing the games.

As for the bolded part, please provide examples.   

Hahaha dude, that's because of the game, not because of the hardware 

@system requirements:

hahahaha... seriously, that's it? 

This is from my computer not 20 minutes ago on max settings for both games in 1680x1050

Oblivion - Avg 28 FPS

Bioshock - Capped at 60 FPS by V-Sync

edit: Grrr photobucket cropped them down and made them jpg....

edit2:

Ok here it is again from another host, they were still converted from bmp to jpg but its in the proper resolution....

Oblivion

Bioshock

Both pics were taken using FRAPS and I just loaded my most recent game and found a good shot with water from each. I didn't do a bunch of searching or anything.

wow a 8800 GTS? dips under 30fps at max?
I guess the framerate drop in Max settings aren't worth the visual enhancement in Oblivion. I like my settings tweaked & slightly lower than absolute max and will never dip under 30fps outdoors w/ E6600 + 1900XT.

but damn, Bioshock looks beautiful. I gotta try this soon.

I think it is because the AA in the oblivion engine is crap, I get better rates with just HDR but even then combat can get crazy and I might dip into the mid 30s.

Holy crap, that terrain texture in Oblivion looks like it came straight out of the Helicopter demo in 3DMark99.

no Linux client for UT3?

disappointing, looks like I might not get it after all if that's true

 You need to change your graphics card as well... I really doubt a X1300 can handle the game. At the very least a X1800 should do it.