Its completely up to you....that said however, I always use OEM Mann filters from FCP Groton or IPD, They usually run about $12-15 for the cabin filter, and about $11 each for the fuel and intake air filter. I tend to avoid any parts-store branded stuff, since its usually made in china or god knows ...

Man, my list is just getting longer:

Done:
Front rotors and pads
Rear rotors and pads
Left Lower control arm
Alignment
both front outer tie rod ends
Oil change
Tranny fluid drain and replace x 2
Cabin Filter
Intake Air Filter
Wipers
Fuel Filter
Serpentine Belt
Brake fluid flush with ATE Super Blue ...

I bought a 99 v70 from ebay (i know, i was asking for it) in Jan of 2009 with 95k miles. I bought it specifically because of the engine photos - it was immaculate. I also lucked out, since the seller specializes in used volvos, so the timing belt was just done. I have put over 28,000 miles on it ...