You're gonna waste more money trying to upgrade that thing than to build a new much more capable PC.

What would be your budget for a new build?

Unfortunately, the computer is dated enough (LGA 775) that major upgrades aren't possible unless you want to rebuild the whole thing. TF2 is a CPU focused game, and you won't find any CPU for that socket/motherboard for a decent price that will give you any huge improvements over your current C2Q. If you want a new CPU, you'd need a new mobo, and then new RAM, then you're basically just building a new PC.

All I could suggest is pick up a newer, cheap GPU. It won't make it like new again but it will improve things. The maximum I would suggest is something like the Radeon R7 250. You could likely get away with a R7 240, which is one step down, but looking on Newegg the 250s are only like 10 bucks more for a good model. It'll certainly be a huge jump up from the current one you have, but you will likely still be held back by the CPU. C2Qs are good processors, but are a bit dated.

Core 2 Quad is about as good as you're gonna get with that motherboard. The upgrade-ability of your computer is directly correlated with how good your motherboard is... A four year old motherboard unfortunately is not gonna cut it. A lot has changed since four years ago, including several new Intel sockets.

As r4pture mentioned, the only thing that will give you any FPS boost is an upgrade to your GPU, but honestly the rest of your rig will give you such a huge bottleneck that its likely not even worth it, you're much better off saving what money you do have for a new computer down the road, if that's possible.

Buy an after market cpu cooler and overclock your cpu is your best bet for that build.

Here's a budget friendly build for you that still has decent power.

PCPartPicker part list / Price breakdown by merchant / Benchmarks

CPU: Intel Core i3-4130 3.4GHz Dual-Core Processor ($116.97 @ OutletPC)
Motherboard: Biostar Hi-Fi B85S3+ Ver. 6.x Micro ATX LGA1150 Motherboard ($59.99 @ Newegg)
Memory: Crucial Ballistix Sport 4GB (1 x 4GB) DDR3-1600 Memory ($40.81 @ Amazon)
Video Card: EVGA GeForce GTX 750 Ti 2GB Video Card ($149.99 @ Amazon)
Total: $367.76
(Prices include shipping, taxes, and discounts when available.)
(Generated by PCPartPicker 2014-03-01 12:26 EST-0500)

You could probably salvage your case, power supply, and HDD. You would have to see if a MicroATX motherboard could fit in your case(or you could just get a full ATX mobo which it more likely supports). If you can salvage your RAM(It would have to be DDR3-1600), then you would save yourself an extra $40.

a couple of hours after this post my computer broke lol

rip my graphics card 2009-2014

i might try just a gpu but ive had problems with my computer all over so i'll probably just wait to get a cheap-ish new build

thanks every1 for the help :)

Doubtful the bios would allow for that, and the psu will undoubtedly be trash.

Would be lovely to have a fps like that for me. I have a fps config as well, still when shit goes everywhere I get 10-20 fps. Yep, my pc sucks. I've learned to live with it anyway, and I think you could too if you don't end up finding a solution. :3