Orange Livebox printer - Maybe OT

I've just purchased a new Vista Home Premium based PC to replace my
aged XP machine.
On the old computer I had the HP 5150 printer connected via USB and
two laptops, one XP the other Vista, accessed the printer over the
network.
Thinking I could replicate the system I duly installed the drivers,
but the laptops couldn't now print via the new PC.

No worries, I'm on Orange with a Livebox so I can connect the printer
to that and use it as a print server - now all computers can print via
the Livebox.

THE PROBLEM:
Whilst I can print small print sizes via the Livebox larger print jobs
don't work. When I word in CAD the print files can easily get to over
50mb and the print spooler doesn't seem to handle it. When I try to
stop it I can't delete it from the spooler with going into the depths
of System 32 and deleting from there. (The strange thing is the
printer spooler in System 32 reports the file as a Shockwave file?)

Anyone had the same problem?
Anyone any suggestions for overcoming it?

Cheers
Steve