Obviously you can use an adapter to convert SATA to IDE. Whether 2.5" IDE(what you have), or 3.5" IDE. If you don't mind it hanging from the laptop if it doesn't fit as designed, that's fine. Of course.
Make sure to get the right adapter, but they're cheap. So you could even get a few and different types and you may need to use M-F adapters to convert things. I've never actually used an adapter that went from a 2.5" connector on a motherboard.. it should work. Make sure you know which side of the IDE is pin1 and which side has pins 41-44 (power). You could post an answer when you've done it, with pictures to show what the adapter looked like.
A warning- Is it possible to plug a 2.5" drive in wrongly and could I break it?
A question worth watching - very related to your question.
Is there a cable that is 2.5" IDE on both ends, or an alternative to plug a SATA drive into an IDE laptop?
It's certainly possible in theory. But I guess (at least if using the IDE-SATA adapter board, and i'm not sure what else you'd use), and if it doesn't fit and you need a cable, you would have an issue finding a 2.5" IDE cable.
I have an idea.. if you can't find a 2.5" IDE cable. I've no idea if this will work. But no harm in trying.
Get 2* 2.5-3.5" adapter cables. Take the 3.5" female ends and connect them with a 3.5" male both sides gender changer. Then you will have built yourself a 2.5" cable!
I'd say ignore the two molex connectors hanging off the cables. The laptop should send power down the 2.5" cable through pins 41-44 to your drive. Presumably a SATA-IDE adapter board if it's a 2.5" adapter board, takes power from the IDE end to power the hard drive, I guess that's how it'd work. That might work!