Just wanted to relpy with the final results....I ended up getting the brake booster replaced. I live in Japan and we have a mandantory vehicle inspection system called "JCI" (I think it's Japan Car Inspection or Insurance). My time was up for the JCI, so I had the Volvo dealer provide a full tune up, and had the brake booster replaced. It ended up costing me about $600 more than the typical JCI, but that included the new brake booster+installation, and they replaced my tourque rod/arm bush and changed out my brake fluids, cleaned my throttle body, etc. My 2001 V70 T5 drives better than it ever has before! Not sure what else these guys at the Volvo dealer did, but I feel like I'm driving a new car.
To be honest, when I first bought this volvo, I had nothing but small malfunctions and troubles, and was having alot of doubts about this car. Now, after driving a temp loaner car (Toyota) for several days during my JCI, plus the great service the Volvo mechanics did on my car, I can honestly say that it was well worth it.
Tech...thanks for all the advice...I'm sure I'll be needing more in the future.