SAVE YOUR MONEY FOR NOW IS WHAT ANY DECENT PERSON WITH HALF A BRAIN WOULD TELL YOU TO DO!
Unless you want to upgrade to play other games that actually take advantage of good hardware.
I would think long and hard about spending money on upgrades for THIS game. If you plan on playing IL2, Lomac, OFP, Farcry or other high end games then yes get the hardware, you won't be disappointed.