Help With purchasing sata 2 Raid set up....

Hey there....
I have recently started building my 1st self built system....

At the moment I have....

Samsung 400G 7200RPM SATAII 16m (HD403LJ)
MSI K9N Platinum (non-SLi)
AMD AM2 5600
Corsair DDRII TWIN2X2048-6400
MSI GeForce 8600GT OC (NX8600GT-T2D256E-OC)

At the moment I have Xp pro sp2 and all install files running on a 100gb partition and my music movies etc on the rest....

Anyways after running 3dmark06 and comparing my results to others with the same system but with different HDD's (unknown what setup or type) my HDD scores where significantly lower...

I am considering purchasing 2 Western Digital 160G SATAII 7200 rpm 8mb HDD's (WD1600JS) and running all programs and xp from a RAID 0 setup and using the samsung as storage.....

Would this be a good upgrade option for a gamer???? Also would the smaller 8mb cache be much riskier in the raid setup???
Or would just 1 10000rpm hdd be a better option or something else???

I am new to all this and have never setup a raid before so any advice would be fantastic....
I also plan on upgrading to vista home premium after xmas purely for directX 10... I am waiting untl then to purchase a new GPU and sound card....

Thanks heaps guys!!! Tom