Does anyone know if there's any PC software utility for editing my SU10's data?

The easiest way to edit a sample for your SU10 is to download a shareware version of CoolEdit. You can manipulate your sample, then set the SU10 to trigger mode, then re-sample.

If you want more editability consider buying Powertracks Pro-Audio for $30. This gives you the ability to save your wave files and edit them as well.

Thanks I have Cool Edit so that's great..Incidentally is there a way of trimming the sample to size for looping etc and reducing memory usage in this midget sampler?

It does have a graphical method for trimming samples. The difficulty is - that there is only 57 seconds of sampling.

I traded in my SU10 for a Roland SP202. I edit all my samples using PowerTracks Pro-Audio to manipulate and create my loops. I trigger sample them into the SP202.

I use the SmartMedia 4MB sounds to give me 4 minutes of sampling time - and I have 5 of these cards that I can use while I'm performing.