Although nothing about game was mentioned, aj2003 specs, mainly the video card, speak for themselves. As my previous post notes, any app load time will be definitely better, but unless you use your computer as Network base or CAD (but then you would not go toward a gaming card but a precision card) or video editing or any other program which are HDD request intensive, there is no noticeable gain to get by going to RAID 0.
I would still get the video card upgrade.
My gaming machine:
P4 2.8 GHz
2 X 512 MHz PC3200 in dual DDR mode
Intel D865PERL MOBO
integrated 6.1 MAX audio
Logitech duo MX mouse and KB
ATI RADEON 9800 PRO