Well I'm planning on buying a new PC sometime in the upcoming weeks and have decided on the one I want, I'm just curious if it will play oblivion maxed out, and what FPS will I get.
Specs:
AMD Athlon II X2 255(3.1GHz)
4GB (2x2GB) DDR3 1333
500GB SATA-II 3.0Gb/s 7200RPM HDD
ATI Radeon HD 5450 512MB PCI Express Graphics
Windows 7 Home Premium 64-Bit
Fairly awful, I imagine.

Reason being, the graphics card. That one is really designed for Home Theatre-type work, not gaming.
The CPU is fine however, if not stellar. 4GB is enough, and yeah, everything else is OK. Just remember to install Oblivion somewhere other than Program Files [or Program Files (x86)] - for example, I use
C:\Games\Bethesda Softworks\Oblivion but you could install it any number of other places. This is vitally important.
So anyway, I'd seriously look at getting a better GPU. You
will appreciate it.
edit: The GTX460 mentioned in the following post is indeed good value, as is the HD6850 and the HD6870. But even a GTS450, or maybe an HD5770, would be a *vast* improvement on the HD5450. Just make sure you buy a good, solid power supply that is powerful enough for the combination of CPU and GPU you end up with, and then some. I recommend looking at Corsair in particular, but some other brands are mostly OK as well (e.g., Antec, Seasonic...) - check out reviews, is my advice, and that goes for every item you're thinking about buying. Takes only a little time, but might save you a *lot* of stress, or worse.