RAID 0 QUESTIONS + SATA II 3G questions

Hello,

I currently have two WD 250 gig hardrives I bought from www.monarchcomputer.com They are the 16MB cache models (not the 8MB) and they are 7200RPM SATA II 3G's models.

I bought these becuase they seemed like a good choice for $125 each compared to the other drives I looked at.

I have several questions:

First- Are these drives any good? Or did I make a mistake.

Second- How much faster performance wise is the SATA II 3G models from the normal SATA? It this somthing you can notice? Is there anything you have to do to notice this, or use it? Explanation about SATA II would be great!

Third- I am running them in RAID 0 as a single drive. How much faster is the RAID 0 then useing them as two normal drives?

I have a dual RAID mobo (ASUS AN8-SLI DELUXE)

Fourth- I also have a Seagate 250 gig ATA drive IDE (not SATA). What would be the best way to set up my PC? Should I use the 500gig RAID 0 combo as my system drive? Or should I use the IDE 250 gig drive as my system drive?

Most important to me is performance everyday, in loading games, copy files, downloads etc..... I am not afraid of losing data in case a drive failed. So- I am thinking I would be best to use the RAID array as m system drive and install windows to that. Will I really notice a difference in performance (and how) if I install to RAID array as opposed to my normal IDE drive ?

Thanks for you help answering my questions about RAID and set up.

-MIKE