~~If you want more RAM, you'll have to find out if you're currently using DDR2 or DDR3 RAM, documentation on P43 boards is really weak I'm having a tough time figuring out what your board supports (conflicting information all over the place). Or if you think you might get a CPU with a fan already included (such as the non-k variant Intel processors, or the non-x AMD AM4 Ryzen processors), you can simply buy new thermal paste and re-apply it when you install your upgraded LGA 775 processor. For example, the CM Hyper 212 EVO ( $38 Amazon, also available w/ $10 Mail-in rebate on Newegg but +$6 shipping) is compatible with the LGA 775 chipset, but will also be compatible with all modern motherboards (LGA2011 & AM4 with an extra bracket) for when you do your full upgrade in the future. You'll probably also want either a new cooler, or at the very least new thermal paste for your upgraded LGA 775 processor (the old stuff on it will be rock hard and unusable). I would highly recommend the QX9650 over the Q6600 at that price (far better performance, don't even consider the Q6600 if you can get the QX9650). ~~Actually, I think the Core 2 Extreme processors may not be compatible with your motherboard, I'll leave that in there until I know otherwise (Core 2 Quad Q6600 would definitely work).~~ It should work, the ASUS P5QL manual states that it does (page 28). Or you can pick up a Q6600 for a slightly lower cost. Here is a modified QX9650, which seems like a great upgrade over what you've got.

Fortunately, you can upgrade to another LGA 775 compatible chip for a modest cost. You could, but your bottleneck is without a doubt your CPU.

Cm hyper 212 evo noise