Is this only partition on your HDD ?
You can expand partition with LiveCD, BUT HDD has to have free space after it (not assigned to other partition).

I recall doing such stuff, resizing partitions, back in the days, booting from floppy, using the commercial software from powerquest, partitionmagic.

These days, there's gparted and parted magic which might be used for the same purpose.

I haven't used any of them recently.

I usually do this by booting from an old version of GParted, but any similar tool of that time (so that it can work on the machine) will do

Thanks for the replies guys. I guess I will look around for period appropriate software. It is the only partition on the drive wil ample free space after it so maybe I can work it out without a reinstall.

You could also possibly boot from USB if you use the Plop boot manager floppy if you want to save burning an older, less resource intensive, version of gparted or parted magic.

If you run fdisk can you see the unpartitioned space?
If you can you could just make a 2nd partition. This is what I do anyway
8GB is plenty for windows (typically I only give it 2-4GB) Games, recovery files, etc all live on D:\ which makes reinstalling windows much less painful

Back in the day, I used Partition Magic. Later switched to Diskeeper, which also worked perfectly on W95 and later. Both were commercial software, and I can't remember what restrictions were on unregistered installs.