My thanks to all who replied to my query. I am now enlightened, perhaps to late!
Why didn't you use the partitioning tool in the Windows 7 installer?
When you get to the part about where to install, there's a "more options" button that allows you to trash your old partitions, create new ones, format etc, before you install...
Simple answer to your question is that I didn't know you could do that and of course didn't look further than the end of my nose.
Was this a Samsung installer app which (possibly) boxed you into Dynamic disk? I would call them and insist they undo it, help you reconfigure as you want it, or RMA the machine.
The best approach is to use Windows 7 Disk Management for pre-installs to shrink as necessary, then for what it can't do (without risk) use free Partiton Wizard bootable CD which we have found works best for Windows 7, having never failed in helping 100+ Resizing/Moving/Conversion operations here.
If you want to take it on yourself, you can remove the data and convert the disk - others may know better but I have never heard of a Dynamic disk than cannot be converted to Basic. Then reinstall from a clean copy of Windows 7 with the partitioning you want, activating with the key on the COA sticker.
Whilst I can't be certain it was the Samsung installer that put Win 7 on the computer, I assume then that that maybe was why I missed the various options.
I shall ring the Samsung Tech department tomorrow to see what advice they can offer and I will report back as, when and if Samsung help out here.