How should I upgrade my computer? [MOVED]

SPEC
Motherboard [KEEP]
EVGA nForce 750i SLI (Socket 775)
CPU [OPTIONAL]
Intel Core 2 Duo E8400 @ 3.00GHz
Memory [OPTIONAL]
4.0GB Dual-Channel DDR2 @ 399MHz (5-5-5-18)
4. Case [KEEP]
Antec 300 Versatile Mini Tower [SSD compatible]
Power supply
I don't know
DVD RW drive [OPTIONAL]
WNKFU SX6BCLMVWPYJ SCSI CdRom Device
Hard disk drive [OPTIONAL]
488GB Seagate ST350032 0AS SCSI Disk Device (488GB)
Seagate ST380811 AS SCSI Disk Device (74 GB)
Video card [KEEP]
NVIDIA GeForce 9800 GT (EVGA)
9. CPU cooler [CHANGE]
I only have 2 fans right now
Thermal compound
I don't know
Operating system [KEEP, I have the disc]
Windows 7 Ultimate 64 bit
Monitor [OPTIONAL]
LG L1752T 1280x1024 pixels
Speaker [CHANGE, if extra $$$ are left]
My speaker right now are crap and would like to change new ones if I don't have to spend too much

PURPOSE
Gaming, ALOT
Movies, when I am not gaming

COST
Expected moderate spending not over it
Keep it under around $300

CONCLUSION
Just tell me if I should spend more $$$ or change hardwares that I want to keep

no need to upgrade, you've got a nice machine. :)

if you're into gaming, the most important thing is the graphics card. it will let you play modern games at high settings.

also, a bigger monitor would be nice, for more pixels and detail - but then you may need a new graphics card to drive all those new extra pixels, and a new graphics card may mean you need a bigger power supply.

There are a few things I can see. First is ram, see if your mobo with allow 800 mhz for the ram and from 4 to 8 gigs, should see a significant performance increase. Second is your psu, go modular with a minimum of 750 watts. Great for cable management. Third is HD, definitely go to an SSD and load you OS on that, maximum performance increase. Fourth, if you wanted to, go to a quad core cpu. Then with the new parts in, get you a good cheap mobo, case and build a rig with you left over parts and sell it to recoup some of your money. If you play your cards right you might come out in the plus column in the end. Win win for everybody.

I think mickey megabyte's idea is more suitable to my needs right now but I'll upgrade my system some other time like bassfisher6522 said and maybe sell it afterward as well.