Upgrading - Need ideas

[serenity]

So I just got the CoolerMaster HAF cases and I'm loving it... It looks so sexy...
Anyway, getting the case has inspired me to upgrade a few more things.

I'll be using it mainly for gaming...
Here's what's in it now:

P5Q Pro Mobo
Intel Wolfdale 3.0 ghz CPU
4 x 1GB Corsair XMS2 1066 RAM
3x Seagate Barracuda 80gb HDD 8mb(RAID 0) -- Kinda Slow, wanna upgrade these...
2x Seagate Barracuda 250gb HDD 16mb (for storage)
Gigabyte ATI 3850 Video Card
Plus all the optical drives and I have a card reader in there too.
It's running XP pro.

Just wondering what upgrades (if any) would be a good idea. Right now I'm looking towards some new Hard Drives but I'm open to some suggestions...

Thanks

[Eagle Eye]

Mobo: Fine
CPU: Assuming thats an E8400 fine just overclock it to 4GHz
Ram: 2x2Gb would better but what you have we'll do (32 bit os and all)
HDD: WD Black or Samsung Spinpoint F1 would be a great choice what size depends on your data needs
Video: GTX280 a solid deal right now or if you're an ATI fan have the budget I'd get a 4870x2 (just wait for the price drops)
Optical Drives: what you have now should do, just replace what breaks
OS: Vista is an option you might consider it even though Windows7 is on the horizon, what I have read going from WinXP to windows 7 won't be a simple task.
PSU: Didn't see one anything less than a 600w currently I'd upgrade, faster videocard, maybe some overclocking a 750+ would do say Corsair or Antec

Good luck and I hope I could help,

EE

[serenity]

yeah some great tips there man, thanks...
Right, forgot to mention the PSU... I have an Antec 600W in there right now...
Yes, the CPU is an E8400.

Reluctant to change to Vista with System 7 almost here... Plus I hate Vista :-P