Stylo

Guild Wars 1.  Hands down the greatest PvP for any MMO style game ever.  The Guild V Guild system is still very active.

This small interview was more insightful than past interviews.  Even though it doesn't reveal a ton of changes it shows they are trying to improve WvW.  Can't wait for the changes.

Re-trait your character for lots of AoE and you'll get lots of badges.

The Q6600 is an outdated processor and all you're doing is buying yourself future headaches.  Guild Wars 2 is a HIGHLY CPU heavy game.  To answer your question directly if the upgrade will help your performance is most likely yes.  But how much of a performance boost is the real question.  You could be looking at just a 5-10 FPS boost.

Read this article about GW 2 and CPUs from the pros.

The only advice I could give you is to pass on that system and bank that $400 even if it takes you another 6 months to a year to save another $400 for a system that will last you 5+ years.

Good Luck.

Save up some extra cash and get something nice. That PC will have issues.  Need to know more about the motherboard as well.  There are tons of Asus boards.

if you're on a budget run this:
CPU:  i5 2500K 3.3 GHz
MB:    ASRock  Z77  LGA 1155 ATX
Vcard:  AMD Radeon  HD 7770 or the AMD Radeon  HD 7850 (This one about $70 more)
PSU:   SeaSonic M12II 620W 80 plus Bronze certified
RAM:  8GB (4GBx2) DDR3/1600MHz Dual Channel Memory

All good components and will run the game very nice.  Don't try and penny pinch and end up with a system you'll completely hate that will ruin your gaming experience.

The parts I listed will run you about $550 to $600 depending on which video card you get.  You'll also obviously need a hard drive and tower if you don't have those already.  Built completely from scratch with a hard drive, tower, OS, and other misc expenses the entire system would run no more than $750 - $800.  And this is a great system.