Slow network

Hi, I occasionally need to transfer files from one PC to another at
home. I recently attempted to transfer a 1.1gb file from an aging
win98 laptop to an XP one. They're both connected via the Netgear
router which I use for interenet access, the win98 one via ethernet
cable, the XP one usually via wifi. The file took around an hour and a
half to be copied, which seems ridiculous to me. I've no idea where to
start to see what the problem is. Both PCs seem fine at downloading
stuff from the internet (albeit the elderly one is a bit slower, but I
think this is just because it's ten years old rather than a connection
speed issue). In fact downloading 1.1gb from the internet would be
much quicker.

I've tried plugging both PCs into ethernet sockets to rule out any
problem with wireless and this made very little difference. I've also
tried turning off virus protection on the machine to which the file is
being transferred.

Any pointers or suggestions? I know I could use a crossover cable and
cut out the router, but I'd like to try to sort out the problem with
the existing setup if possible.