Installing 2nd SATA Hard Drive-- PROBLEMS!!

Hi,

I just bought a new Seagate Barracude SATA 160GB HD. I already have a 300GB SATA hard drive installed on my computer. I have a ASUS A8N-SLI Premium Motherboard that has 4 Sata connectors. My main 300gig HD is on number 3 on the sata connectors on the motherboard. I tried installing the new 160 gig hd on number 4 and heres what happened. The computer seemed to want to boot up the new one first it think.....because after I installed I went into the BIOS to see that the new HD was recognized on number 4 sata..which it was...rebooted got to the windows boot up screen and then it automatically reboots which is what it does every time until I took out...or just simply unplugged the new HD from the number 4 sata connector and it boots up just fine from my main drive. Any thoughts or suggestions on what I should do? Should I try moving my old HD from Sata 3 to Sata 1 and putting the new HD on Sata 2? Also, How do I know when I go into the BIOS if my old hard drive is still the Primary one which I want to keep it as the primary one. This second one is just to relieve some space off my old 300 gig drive...which its only about 4 months old anyway...What else should I do or check for in the BIOS if anything..Thanks for any help...

Joey

AMD Athlon 64 X2 3800 cpu
1.5 gigs SDRAM
Asus A8N-SLI Premium Motherboard
Dual Nvidia 6800XT Video cards
300 GB Seagate Sata HD