That's rather odd; Ubuntu normally detects an existing Windows install and configures Grub to dual-boot either Linux or Windows.
There are quite a few variables here. Firstly, are you sure that your PATA drive is drive C? Windows is only capable of booting from the first drive, and so if you installed a blank SATA disk and the BIOS detects it first, then you can only boot Windows off that, regardless of which OS you disk in the BIOS menu. (But there is a trick using GRUB to get around this.)
Have you tried unplugging the SATA drive and seeing if Windows will boot then?
If it doesn't, then it looks like Grub installed itself to the master boot record of the first hard disk, which would be reasonably normal for a dual-boot installation. Grub isn't used by a regular Windows install, but it is often used by Linux systems to present a dual-boot menu, as it's perfectly capable of booting Windows.
There are two possible solutions here: The first is to re-install the Windows bootloader, which will wipe Grub from your “C:” drive and should fix Windows, but this might break your Linux boot.
The second option is to configure Grub to boot your Windows partition. To do this, it uses a chainloader to load the Windows system. This is a little involved, but you can find instructions at http://www.linuxselfhelp.com/gnu/gru...b_4.html#SEC14
. If your PATA drive isn't the first disk identified by the BIOS, then you way also need to swap the disks as described at http://www.linuxselfhelp.com/gnu/gru...b_4.html#SEC21