Odd W7 probvlems - advice needed...

I recently upgraded my system to W7 Pro. H/W is an Asus P5Q Pro, 4Gb and an Intel quad core which has all been running XP fine for about a year. Bought a new 500G drive to put W7 on.

Installation went fine and it found drivers for everything except the NIC which i got from the Asus site.
It ran mostly ok for a few weeks but with the occasional 'stop dead' - no BSOD, no nothing. Then it started to occasionally hang for about 20 secs at a time.
Ran HDTune and it found some damaged block - but I'm not sure if they are really damaged or if W7 has just decided to mark them as such.
Memtest says all memory OK.
Updated to mobo drivers from Asus site and things got much worse. e.g. CD drives disappeared until I rolled back the Marvel drivers. Now VERY flaky.

I'm resigned to doing a complete re-install and I'll get a new HD and new graphics card (Currently FireGL V3350 which has no speficic W7 drivers).

Questions?
Stick with the P5Q?? (Worked ok with XP)
If so, stick with W7 installed drivers or go with Asus ones? (Caused grief this time).

I don't mind the rebuild but I'd be happier if I knew what was causing the problems

Any thoughts
Thanks
Steve

Get another graphics card.

No problem with P5Q

no BSOD, no nothing. Then it started to occasionally hang for about 20 secs at a time.

Thats the clue.

Not offhand,

I generally use Novatech or Amazon.