Dual Boot Winnt4 question

[pmistry 0]

I got a PC running Windows 98 on a 4 GB FAT32 drive. I have a second 20 GB hard drive which I want to install Windows NT4 Workstation on to but I can't get it to work. I don't want a real dual boot, just juggle the hard disks and boot an OS off of it. FDISK won't let me make the second disk active, and thus Winnt 4 won't install. Also my BIOS is old so it won't recognize disks larger than 8.4GB, so I had to use EZ BIOS. My questions are how can I set up this juggling operation for my PC? And will EZ BIOS work with Winnt4?