Will my new built computer be able to handle Dolphin properly?

[Diathorus]

Hello all. As you can see I have a terrible PC.
So... if I'm lucky I can get a new one soon, and this is where I'm aiming @:

The specs are (self built PC)
AMD Phenom X3 8250 1.9 GHZ; (Aiming to OC it)
3 GB DDR2 667 MHZ;
ATI HD3450 HDMI 1 GB HyperMemory or nVidia 9400GT 1024 MB
(Which GPU should I choose?)
I'll be running this with Windows XP SP3 (fresh)
Don't think this is important but motherboard is Biostar.

Should I be able to reach decent speeds, let's say games like SSBB and Twilight Princess (not aiming at 100% speed but let's say...78%)?
& They're PAL version (Europe), I heard that also affects FPS?

Thanks in advance.