You can save a lot of cash buying Windows 7 or 8, 8.1 and using the free upgrade offer instead of buying the OS for the whole price.
he said he IS using windows 10
now...
windows 10
i forgot to ask this question before, how old is that PSU you have?
also, YOUR RAM IS THE CAUSE OF ALL YOUR PROBLEMS.
not only is it a slow speed, you also have virtually nothing to use when windows 10 inevitably eats up 2 of the 3 GB.
now play bf4 which uses around 2-3GB of ram...
...that's a lot of stuff hitting the page file and i'm pretty sure you have a regular harddrive.
a ram upgrade is a no brainer here, nothing will improve until you make a ram upgrade.
the problem i see here imo in the gpu vs cpu battle is...
with battlefield 4 and fallout 4 on that list, those games hit the cpu just as hard as the gpu.
so a gpu upgrade serves no real benefit for those two games, maybe i'm underrating the e6700 but i don't think it will.
but a cpu upgrade will serve no real benefit for a lot of other games like star wars battlefront.
a gpu upgrade is a gamble but will ultimately benefit you in the long term since you plan on upgrading the CPU AGAIN if you go the cpu route.
honestly i think you would benefit the most from a psu upgrade sooner rather then later if it's older.
but if it's a younger psu which i doubt make the upgrade when you pull off the upgrade for your stronger CPU.
if you make the psu upgrade delay your gpu upgrade until you have a bit more money to afford a gtx 950
http://www.newegg.com/Product/Product.aspx?Item=N82E16814487156&cm_re=nvidia_gtx_950-_-14-487-156-_-Productit shouldn't be much.
or if you want to go the CPU route i honestly recommend the amd FX series cpus and
sticking to them. (for this next motherboard at least)
it is a more readily available choice and when paired with a gtx 950 you really couldn't ask for more.
but if you go with something more powerful then a 950 then the cpu is going to become a problem.
and you should be able to make the upgrade to the newer cpu sooner.
an option i recommend is buy the ram and psu if its older and see if the cpu is really that bad, if you still think it is then go the cpu route, if you don't go the gpu route.
Windows 10 home is $110 USD, pro $200.
You can get a Windows 8.1 key from /r/Microsoftsoftwareswap for about $24 usd, you would save money and you would be able to buy better parts.
are you dyslexic?