I have a 1tb hard drive and I am quickly running out of space, I am highly considering getting 2 more 1 tb hard drive the same model and then use them in a RAID 5 configuration. However I might be being given a new motherboard soon, and I was wandering if the 3 hard drive are transferable and I would have all of my data and the same windows as before on my new motherboard, or as it is a new motherboard will I need to re-install windows anyway?
a separate raid controller is the way to go... but like mentioned you should separate your O/S on either a separate partition of the array or on a spearate drive all together... here is another wrinkle that you may want to consider... use Virtual Box to create a second "machine" on the same array. this way you can move your "host" o/s with little or no trouble then... the guest machines can move with little or no hassle from hardware
paul makes a good point. you should consider using intel matrix raid to create seperate arrays. Low end raid 5 like the ich10r provides can be a bit slow. You could take 100 GB from each drive to create a 300GB raid 0 array for the OS and programs. and a use the rest of the space (i think a total of 1.8TB) for the RAID 5. Make sure you create the RAID 0 array first, and that you disable indexing on the RAID 5 array in windows.
If the RAID card is out of your price range, and you plan on sticking with intel for awhile then you should be fine without it. but if your the type to upgrade every year and a half or so consider the RAID card for a future upgrade.