Doesn't pick up old SATA drive...

Hi
I have a sata drive, with windows, all prog files etc. This in windows is partitioned into c:\ and d:\.

I put in a new IDE (pata) drive, as I want to install Slackware 10.1 on it (and for it to load up only when i have a booting flopping in there for linux). Anyway, so i connect it all up, but it comes up with an error about it can't find a system disk, please insert one. I put in cd 1 of slackware in the cd drive and it worked, so for some reason it is ignoring my SATA drive. I disconeed my IDE drive, and now windows loads as normal

what can I do to fix this?
thanks

Check the BIOS boot order.

Also, what motherboard you got?

asus a7n8x-e Dlx

Check the BIOS boot order doesn't have SCSI before IDE-0, CDROM or both.