ok, have got the mac instal going, but not entirely sure I'm on track - it took 3 attempts to ge the instal cd going/not sure why......then when it got into the start up screen I clicked on disk utilities top left and in the left window of the screen which came up I had :
1. 1TB WDC WD1001FALS...
2. Macintosh HD
3. untitled
OPTIARD DVD RW AD-5
MAC OS X INSTAL DVD

I selected number 1 ( on the other 2 there was no partition tab coming up when I selected them).......clicked on partition, which was set to "current" for volume scheme ....changed that to 1 and applied; checked that GUID was checked. The message that came up was : "are u sure? this will delete mac hd"......I went for it and now have "untitled disk 1" and am continuing with set up......will report back ! * it shows 999.86GB.

Thanks for getting me this far, what a relief.

(hello again mr.plow - we're now back in the UK and enjoying landline broadband so no more faffing around with usb/dongles!)