If you have XP it can write to CD-R without extra programs
Vista/7 can write to CD-R and DVD-R (or DVD+R) without extra programs
What happens if you insert a DVD containing more than 700MB of data ?
There are a number of freeware programs available to write Data to CD & DVD's
These are often restricted versions of commercial programs such as Nero, NCH Expressburn, ImgBurn, deepburner. smartburn ......