Stupid Question but don't ignore
 

2 computers.

1 with Slack 9, the other with XP.

I was wondering if it was possible for the XP comp to be able to network boot into linux?

If its possible, could someone point me in the right direction to get this working?

You can network boot from a floppy(LOAF). Or from a CD like Knoppix. I'm not sure what you are trying to do, but I am sure that I don't understand the question.

You have 2 computers, Computer 1 with WinXP and Computer 2 with Slack 9, and you want to be able to use Linux on the XP computer from time to time ?

The solution to your problem, as I understand it, is to partition your XP machine into a dual boot XP / Slack 9 system and leave the other computer as it is (just Slack 9). Then when you need to use Linux on Computer 1 you simply exit WindowsXP and boot up the Linux partition.

more or less, have the XP computer boot into my linux...