Vista freezes when installing any program

I just installed Vista Home Premium 64-bit on my custom built computer. When
ever I install something Vista freezes until the program is installed, it
won't let me do anything else, except move the mouse. It has done this right
from the start when I installed it with none of my programs installed yet,
which I would assume a driver issue, but I have all the latest drivers for
my motherboard and videocard. It even does it when Vista is updating and
installing the updates. I can click on something else and it will come up but
it takes a long time. And is it normal for Vista to take 2 to 3 times longer
then XP to install big programs. For instance I installed COD4 last night
and took over an hour.

AMD 4200+ AM2
2 Gig RAM
500 Gig hard drive <---Vista Installed on this
300 Gig hard drive <----XP Installed on this
320 Gig hard drive
Dvd Rom
Dvd Burner
850 Watt PS
dual 8800 GTS Geforce graphics SLi'd

Any help you guys have would be appreicated