Yes, you should overclock your QDR-FSB but you should only attempt this after purchasing a good after market cooling solution and doing some homework.
If you want faster memory just purchase some faster memory then run it at the spec speed using a stable divider. As far are overclocking memory goes, there aren't many reasons to do that anymore because you can just purchase memory that runs at the limit of your board.
The fact of the matter is that overclocking your CPU is by far the biggest improvment in overall performance and speed that you can do to your computer. It will make all computing processes move faster and can increase gaming performance substantially.
But it's not worth doing if you don't take the time to get your system truely stable. I like using Prime Blend test for this. I have also written a guide on how to dial in your system using the GTLVref adjustments which can be very important to gaining stablity when overclocking.
Q9650 4050Mhz Blendstable GTLVref SHORTCUT
Are there any risks,...yes, but then it's also risky building your own computer, but that doesn't stop us from doing it now does it?
Don't let someone who has never even attempted to overclock and obviously knows nothing about it tell you it's a gimmick and that it will only destroy your computer. Sorry man but that analogy is utterly rediculous. Getting advice about overclocking from someone who has never even tried just isn't right.
You aren't about to "lose" your entire system by overclocking a 150 dollar CPU. Q6600's are good for about 3.6GHz for 24/7 operation. The fact of the matter is that parts that aren't overclocked burn out all the time. Memory goes bad for no reason, PSU's go out for no reason, CPU's, although rare, can just give up the ghost for no reason at all, HDD's also are famous for expiring for no reason at all, motherboards also can expire for no reason even when running at stock settings.
Overclocking may increase those odd's on some parts but as long as the extra heat is controlled it's usually not a problem.
If CPU's aren't designed for overclocking then why do the very expensive QX series CPU's have unlocked multi's? In fact why does just about every CPU produced have multi's that can be used for overclocking if they aren't made for it? Or is that also a marketing "gimmick"? :sarc: