If it's not the OS drive you can create the partition in PQMagic and NT will use it fine, Disk Manager strangely says it's a 10G partition on a 4G disk but it works.
If it is the OS partition and you're still in the process of installing, you have to pull atapi.sys from SP4 (or up), run winnt to start the install in DOS, replace the atapi.sys in the install dir with the one from SP4 then reboot and it should be OK.