New RAID setup question

[LLBDTiberio]

Hi guys, just a quick question regarding RAID.
I'm soon purchasing another Western Digital drive for my PC and I want to set it up in RAID0 with my already installed WD250GB drive.
Would I need to purchase the EXACT same drive (i.e 250gb) or can I purchase a different sized harddrive, as long as its the same model?
If this is not the case, is there any way I can get a 250gb and a 500gb drive to be recognised as one?
I really don't want to have to go out and get 2 new HD's when one could suffice

 

[LLBDTiberio]

Ah ok, was a bit confused about this.
Will purchase 2X 250gb then, it's not like my V1000 won't be able to accomodate them
Will I need any specific cables for a 3X 250GB Raid0 configuration then?
Not sure which cables are needed or if I have enough.