Will this computer be able to handle Skyrim on ultra/Battlefield 3?

The GT 630 is not a gaming card. I will say no for both. BF3 probably will not even play on the lowest setting and Skyrim you may be able to play on a low resolution on a very low graphical setting. Nothing that would look to great. I would shoot for something like a GTX560Ti to play at a decent graphical setting.

If you expect to play Ultra setting on Battlefield 3, you will need something along the lines of a GTX670. My GTX580 wouldn't even handle Ultra. This is assuming 1920x1080 @60FPS.

The PC in that link also looks like a slim model. I would stay away from those if you intend to game. There are very few small form factor gaming cards, and they tend to be very low end.
 
The PC you linked isnt even made for gaming.If you really want a good PC you should build it on your own!

I dont know what your budget is but this probably fits in it.

PCPartPicker part list / Price breakdown by merchant / Benchmarks

CPU: Intel Core i5-3450 3.1GHz Quad-Core Processor ($149.99 @ Microcenter)
Motherboard: MSI H77MA-G43 Micro ATX LGA1155 Motherboard ($44.98 @ NCIX US)
Memory: Kingston Blu 8GB (2 x 4GB) DDR3-1600 Memory ($35.99 @ Newegg)
Hard Drive: Seagate Barracuda 1TB 3.5" 7200RPM Internal Hard Drive ($77.99 @ NCIX US)
Video Card: MSI Radeon HD 7950 3GB Video Card ($304.99 @ NCIX US)
Case: Antec One ATX Mid Tower Case ($39.98 @ NCIX US)
Power Supply: OCZ 600W ATX12V / EPS12V Power Supply ($39.98 @ NCIX US)
Optical Drive: LG GH24NS90 DVD/CD Writer ($16.99 @ Newegg)
Total: $710.89
(Prices include shipping and discounts when available.)
(Generated by PCPartPicker 2012-07-31 12:31 EDT-0400)

That a MUCH more powerfull PC