Is it possible to have say 5-6 disks on a pc to show as one massive drive? I have knocked a pc together with a few drives in, using an old gigabyte Raid motherboard, and want to stick it away somewhere with just 1 network drive to it. Is it possible?

Yes - though you'll need to use LVM or something similar. Win2K and WinXP should support it - SuSE Linux 8.2+ has also.

If it's a RAID motherboard, they you ought to be able to do it in hardware. Be careful though : if you make a RAID 0 drive, which is just striping all the data accross all drives, you will get maximum space and speed, but if one drive fails, you lose the lot.
Better to go with RAID 5, which reduces the capacity of the raid by one drive, but is resistant to failures - one drive fails and you lose NO data. 2 drives fail and you still lose the lot though, so it would need monitoring.

You can do this in software as well, but it's slower and possibly less reslient.

Ok, so what tools do you think I need to load on the machine before I stash it away? Some sort of remote desktop, VNC or terminal server? Anything else I should use, maybe some sort of disk defrag tool? Its based on an XP install, never tried linux, Im trying to stick with what I know first of all.

Got that, I use daemon tools. I was hoping for maybe a web based interface of somesort. I guess web vnc will be ok if slow.

if it is Windows XP, use remote desktop connection. This uses terminal services and is far more responsive than VNC.

If its on a lan, u can try UltraVNC with its "Mirror Video Driver":

http://ultravnc.sourceforge.net/