Yes, SATA and IDE can co-exist. But how simple it will be depends on whether you want to clone the entire old OS install from the old drive to the SATA or just copy your data and do a clean install.
I would recommend a clean install of Windows and then copy over your data.
You CAN clone the drive (with Norton Ghost or some other utility) but then you'll have to perform a boot repair at a minimum (to allow Windows to boot from a different hardware address than it used to) or a repair install of WinXP at worst (more likely).
Either way make sure to configure the BIOS to specify the SATA drive to be a boot device BEFORE the IDE drive or it'll try to boot from the IDE drive. Your boot order in BIOS should be floppy->cdrom->SATA. You shouldn't even list an IDE drive as bootable.