upgrade complete
now running with 1 gig and one slot to spare.
With hindsight, I wish I had just purchased the 2 x 1gb sims as that was not an easy or fun task to do.
Gordy's video made it quite straight forward though.
Big thanks to all who helped. Info on this thread was very valuable to someone new to macs.
As a side issue is there any places that would want my 2 x 256 sims ?