I did it after formatting the hd, but the BIOS originally on the mainboard (F6) was also supposed to support LBA 48 and work properly.
I've used Seagate DIscWizard and Partition Magic to try to find the rest of the 250 gb. I thought maybe they were as unformatted space after the 137 gb partition, but the applications just find 137 gb as the whole disc, and that happens in windows xp sp2, BUT also running the boot cd of DiscWizard with no OS installed.
Another thing. In the BIOS, inside Standard CMOS Featutes, the IDE Channel 0 and 1 (the "Classic" ones, connected with IDE), as access mode let me choose between CHS, LBA, Large or Auto.
IDE Channel 2,3,4,5 (the SATA-II) just let me choose between Large or Auto. NO LBA OPTION. By default, the option is Auto. With this one detects 137 gb, and everything works but i lose almost 120 gb. If I change to Large (NOT LBA, there is no such option) the size of the hd detected is 128 gb and the OS is unable to boot.
I've written to the Gigabyte (the mainboard company) and I'm waiting for an answer, but every suggestion is welcome mailpup.