Is the boot order screen listing the drives by name/brand -- in which case it has probably recognised the drive.
I'm not sure what else to recommend if you don't know what you're doing.
In this situation I would switch boot order to CD/DVD first and try inserting a Win7 or WinXP or Win98 install disk and see if the computer can boot from that (though obviously don't try installing Windows again). This would help narrow down whether the fault is with the computer or the hard drive.
I suspect you need to take the computer to a repair guy or a friend who's good with computers.