If your motherboard can handle a Q9550 and give it a mild overclock, you could reach 3.2ghz(and beyond) X 4 for a mere $230. That should definitely fix your apparent processing bind. As far as utilization/time/reliability; the two things that will significantly impact the life of your processor are excess heat and excess voltage. If those two things are under control, I don't worry about it.

Beyond this, you will want more ram (and an x64 OS) when you go to 5box. Seeing how Windows 7 is free and DDR2 is almost free, I would do this before making a switch to hardware boxing.