Hi all,
 
I just was assembling my new computer. I purchased an EVGA nForce 750i SLI FTW Motherboard, and a Western Digital Raptor-X 150GB hard drive. My question is, can I connect the hard drive (sata1 correct?) into the SATA2 ports on the mobo? It appears it only has 4 x sata2 ports, and no sata1 ports. I wasnt aware there was a such thing as sata2 till i read through manual while assembling.

There should be no problem. Most SATA 2 hard drives are compatible with most SATA 1 controllers. Also, all SATA 2 controllers should be compatible with SATA 1 hard drives.

He asked about connecting SATA 1 HD to motherboard with SATA 2 ....
 
I also have same problem my mobo (asus p5n-t deluxe) does not detect raptor wd1500adfd in BIOS. Nothing...
 
I'm not sure if its problem with compability or my raptor is just foulty and there is NO INFORMATION ABOUT CONNECTING SATA1 HD's TO SATA2 MOBO's ON WHOLE INTERNET...
 
So if there is anyone who knows, please let us know. Thank you VERY much in advance.

This is why the terms "SATA 1" and "SATA 2" are incorrect -- there is no such thing.  Saying it as "1" and "2" implies that there are two separate standards.  There are not.  SATA is one standard..
 
ALL SATA devices are compatible with each other, by definition.
 
The only (rare) exception is that there are some older SATA controllers that do not support the 150/300 MB/sec autonegotiation process.  For these controllers, there is a jumper on your hard drive that can be installed that forces the hard drive to operate at 150 MB/sec and skip the negotiation process.
 
Otherwise, if you have a SATA controller and a SATA hard drive, plug it in and it will work.

Clear answer, thanks. Then it means my raptor is foulty? because BIOS doesnt see it

Yes, in all likelihood you have a bad Raptor.  Try it in another computer to confirm, if it still can't be seen by the BIOS, RMA it.