So exactly how many os's can Grub handle?
 

Im thinking of joining the testing of FC4. Currently I have WinXP and Fedora Core 3 in my main HD. I have a second one with my music files, and like 20 Gs of space. So I was thinking on installing FC4t1 on the 2nd HD and keep my FC3 right where it is, just in case FC4t1 goes boom on me.

The thing is: is this possible? Can Grub handle 3 os's on 2 separate HDs? Should I really do this or just wait till the real thing comes out (FC4) and replace my FC3?

Yes and Go for it.
 

Grub can handle as many OSs as you disire to type into the file. because it runs from the MBR and reads a file on a specified partion. Using it's knowledge of the hardware to locate those other drives and partions.

I'm not a great expert on Grub or Lilo for that matter. a few weeks ago I was doing the same thing. I had two HDs one 80 G and one 20 G each cut into 10 G partions.

I got 7 OSs to boot from one MBR of Grub. Then the 20 G drive promtly took a dump. Which wasn't a problem I just deleted the lines in the file partaining to that drive And I was back in business runing 5 OSs.

Of course 80 G split by 10 gives me 8 so I still have room for 3 more when and if I decide to.

grub can certainly handle anything you can throw at it...it simply maps boot areas of OS's. Problems come in when different types of drives i.e. SATA and Scsi. Grub is the most versitle boot loader around.