There is a "magic" year where slushboxes became dependable. As you are in US I recon you are looking at automatic. This it's worth checking if you are buying one of these cars. Usual symptom is hunting when shifting from 2nd to 3rd and harsh shifing.
Check this forum:
2001-2007 XC70 (V70XC) - Volvo XC Forums
And read on topic of "B4 servo cover".
Other than that, it's a solid car.
Yeah, one more thing. Those equipped with visco-4WD are more or less FWD and are not t be considered 4WD cars. Not that most people will ever notice...
Later Haldex-equipped work much better on snow.