You can use DVD-R and DVD-RW, only the DVD-RW is rewritable. DVD-R's are write once only.
Don't buy the cheapest unbranded media - buy a premium brand and you shouldn't have any problems. Try a few manufacturers and see which you prefer and which gives you the best results. I am using Verbatim and Discrite media and haven't yet had a failure (At least not one attributable to the discs 
)
They don't appear to stock DVD's, the only things they seem to stock are CD-R's and most of them are unbranded.
Have a look at http://www.medeainternational.com - don't forget to do a google search to find other sellers - you can then let us know how you get on 
Thanks for the helpful suggestions Guys. I've nipped up to my most local store selling DVD media and bought some branded DVD-RW discs (TDK as these are the only ones they had in stock.) Not had time to try them out yet tho'
