First off what raid are you going to create? Raid 0 or 1?
To use raid 0 you really should use 2 identicle size HD's
To use raid 1 with 2 different size HD's you will be limited to the smaller of the 2 drives for space so they can be mirrored.
So if creating raid 0 with identicle HD's I would use the intell ich5r on that board.
If creating raid 1 you will have to use the promise raid controller since you can only create raid 0 if using the intell ich5r on that board.
Hard drive conections TO SATA RAID 1/2 for Promise on MB
Hard drive conections TO SATA 1/2 FOR Intel on MB
Make sure you have made the drivers disk for which one you are going to choose, you can find the drivers on your MB disk.
In the bios for the intell controller go to IDE configuration and make sure these are set to:
Onboard IDE operate mode= enhanced mode
Enhanced mode support on = S-ATA
Configure S-ATA as raid = yes
Serial ATA bootrom = enabled
Save changes and then on boot up (hit ctrl-I) to enter the intell raid set up.
To use the promise raid controller the settings in the bios I believe are the same except for the Serial ATA bootrom which I can't remember if this gets set to enable or dsiable for the Promise.(I think it may be set to disable for the Promise because ATA Bootrom must be enabled for the intell)
Save changes and on reboot hit Ctrl-F to enter promise fast track set up.
You will still have to re format your HD's after you set up you raid array.
Thats about all I can remember off the top of my head,
, if you have the manual for your board it explains alot on how to set up each raid array once you are in the set up program in the back of the manual.
Hope this helps you out with setting up your raid...GOOD LUCK