Can I convert a Blu-ray disc to DVD? If I have the original BD?

if so what do I need?

I dont know how or what you need but Ive downloaded a couple of avi's from mi2 bluray coverts and there really good quality

done Saw v 1.75gb HD avi

You will need to rip the blu-ray first mate. Then convert it to vob.

Try looking at doom9.org for some ripping software.

good old slysoft "anydvd hd" will sort you out

and have a look here Blu-ray Ripper - 5 ways to rip Bluray, free Blu-ray ripper for other tips

Cheers Gents

I have been given a lovefilm subscription with 17 rentals. So I will see some rippage happening soon.