Dual-booting 98 and NT is a bitch due to incompatible file systems. You're stuck with FAT16, and thus 2GB max partition, for your boot drive and you have to choose which OS can access which partitons (formatted in either FAT32 or NTFS) if you want partitions larger than 2GB.
You can get drivers called "FAT32 for NT" and "NTFS for W98", which will allow both OSes to read all partitions but you'll still be stuck with FAT16 for the boot partition. However, they cost a bit.
You could make a 2GB boot (primary) partition for your OSes and apps and format the rest of the disc (secondary partiton) in NTFS and store (non recording) data there. Then format your RAID setup in either NTFS or FAT32 depending on what OS you'll be using when recording.
Which OS to run depends on what your soundcard and your recording SW works best with.
Another solution, which was what I did before I switched to W2k, is (assuming w98 for games NT for recording) to make the FAT16 boot partition, format the secondary partitoin on that drive in FAT32 and format your audio drive in NTFS. That way, you cannot access the drives with the wrong file system from each OS but you souldn't need to access the audio drive when you're in W98 and you shouldn't need to access your games/mp3/etc drive when recording. Although you'll have three partitions, both OSes will show only two, the boot partition and the one with the correct file system.
As you can see, you don't want to dual boot w98 and NT.
FAT16 is (apparently) faster than FAT32 and NTFS but it is limited to 2GB partitions, which makes it a poor choice for your audio drive.
/Ola