Juan,

Specific to that generation of V70/S70 -- find out whether the electronic throttle module has been replaced, and at what mileage if it has, it is generally a 50-60k miles item and about $1000 to replace. Also, check if the ABS controller has been replaced and what mileage as it is also a high failure rate item.

Specific to the V70XC -- check for tire rotation records and tire replacement records to make sure they've protected the AWD system from unusal tire diameter differences.

Also you might want to see what the brake pad/rotor replacement records are, for an XC you should expect rear brakes replaced about 2x the fronts. If the ratio of fronts to rear pads isn't 2x (more rear), then I'd wonder about how hard if it hasn't seen some hard service.

Beyond that, do your research on that era V70 for all the other items. Also, with all the ETM (electronic throttle) failures and other maintenance items, you can drive a hard bargin for one of these cars used, people are getting rid of them and there's a glut.