Any pointers in the right direction would be more than appreciated, thanks
in advance.

As a quick, cheap fix, just upgrade your processor and maybe some extra
memory.
I started video editing on a duron 950 on a K7S5A , did it all faultlessly
but took a time. I've now stuck a duron 1800 in now with 512k RAM and
rendering has speeded up somewhat. You will also need a fan to match your
new processor, I got one for a 3GHz and it keeps the chip very cool, 36 degs
when its been rendering for over a hour.

Bill.