You have a choice: New MObo's normally come with at least 2x IDE channels, and 4x SATA connections. If you change your motherboard (and only have an OEM copy of Windows) You are going to fall foul of the licensing rules (sometimes MS will give you an activation key, sometimes they won't)
If you have a full retail copy, then you are of course fine. It's not as simple as just plugging in the old drives and off you go though...A motherboard replacement will require re-installation of your programmes from the media provided with them.
Best course of action prior to undertaking the upgrade is to backup all your data (pictures, music etc.) to DVD or CD. At least you won't lose them if you have to re-format and start again (recommended)
You really would be better off using the SATA drives in your new system, and using the IDE channels for your optical drives....Either way you will have to buy SATA DVD or SATA HDD drives for the newbie.