I have never seen a IDE/SATA converter.  I have seen an external USB device that can plug into IDE or SATA laptop HDD (it mighta had desktop SATA, but I don't think it had desktop IDE).  I would suggest getting an external enclosure for your new SATA HDD (external enclosures use USB usually).

Some of the newest motherboards have only 1 IDE drive, or none at all, relying on SATA instead.  Not only is the narrower ribbon much easier to deal with in a case, but it's generally a better connection too (because of having several wires in parallel, which create a small electromagnetic field when current flows through them, bits passed through IDE have to go through at least triple-checking every single bit).

He asked about pci adapters.

Unless you're seriously hd crazy and will do multiple raid arrays later, I'd go ahead and use the above linked adapter though.  Just hooking up one drive to one port till you get a new mobo is overkill for buying a pci adapter, they're more for people that need more.  I don't know that I'd trust the cheaper ones in that list.