Got a new mobo

[acidreamer]

Ok, so im planning on installing a new mobo and cpu tomorrow. now, i read on some other posts i would have to re install windows. now, the pc i have came with windows on it and i dont have a cd. another thing i read is that i can partition the hard drive and be able to boot from it with the new mobo. another thing that i read, is that sometimes it will work if you just put it in. but im changing from an nvidia chipset to ati. i need a way to install the new mobo, but being able to still have windows afterwards. im hoping that making a partition on the hd will help..
new mobo
MSI 785G HDMI (Am2+ Socket)
new cpu
AMD Phenom II X4 955
what i have now
pegatron mobo(came with compaq pc)
cpu
AMD Athlon II X2 250
also, another thing that came to mind, is there a way on the new mobo i can set the path to my new hd location for windows to boot from? using the bios of course
thanks in advance

 

[acidreamer]

also, im running windows 7. which i hear takes mobo replacements quite well. i just want some answers before i go into this. this is also my first time doing this..

 

[acidreamer]

im reading all the articles i can on this. now, since my version of windows 7 is oem, it will become unactivated when i put the new mobo in..right? if so, can i just reactivate it via telephone? telling microsoft my old mobo died and had to replace it or something?