MY New PC Keeps Re-Booting

Just threw my new build together(Asus M2n-E,2gb DDR,2.6Ghz Am2 dual core of course,360gb Sata with no OS) Well after my cpu problem(having no cooling system, I've bought an Cooler Master AquaGate S1,
Now that it's put all together, I have to create a partition on my 360gb hdd to install Vista home basic, SO I've plugged my current hdd(Xp Pro) into it to do so and when i turn it on it boots up then gopes to choose how you want to start windows(Safe mode{with networking or command -prompt) but I chose Start normally(one that always works), then it show a blue rectangle and some yellow text on it for about 0.5 seconds then it just goes and BOOTS up AGAIN. Help, DO I NEED THE M2N-E DRIVERS9tried using cd got m nowhere and the asus site did'nt) OR IS IT SOMETING ELSE. HELP ME AND I'LL HUG YOU