Right now I have a 400gb drive with an xp on it and an 80gb with another xp and 7 on that.
so far ive been using the 7 on the 80, however still officially booting off my 400gb drive.
Now I want to isolate it so I unplug all my other hdds so I get the invalid disk error. How can I repair it to let me load just xp for now, 7 isnt a concern.

I did bootcfg and added in the xp install and I did fixboot.
Still wont load up. do I need fixmbr as well?

The 80GB has XP and Win7? They are installed on different partitions? The 80GB needs to be set "active". You were booting off 400GB. Boot.ini is XP and bootcfg is Vista/Win7 (I believe).

The reason why I on use 1 OS per computer.

nod nod. yea the 80gb has 2 partitions, 1 with an XP and other with 7. (technically has 4 partitions, but 2 are blank fuck arounds)
im fairly certain it was active.
yea boot.ini is for xp and bootcfg for vista/7.
But Im not concerned with it seeing 7 at all or anything. bootcfg on xp recovery only sees the xp which I want. i just wasnt sure if i had to fixmbr asw ell since it always has that warning about losin partitions and shit.

Only one partition can be set as active...

nod, the xp drive is the one marked active. Ill try to edit my main 400 to see it and add to the boot order in the meantime to make sure its even configured properly.

you can always use grub or lilo on an xp machine

also there is an older app called acronis boot selector that will search out your installed os' and give you a boot menu. finds everything

i've used it a couple of times when I only had one os and the it got the boot sector whacked, saved the day and then I just set it for no seconds on menu time