What is the main difference between a dvdrom and a cd writer? (hardware wise) Is it a different laser? maybe someone can send me a site for how dvd rom or writer are built?

The only difference I can think of is, like you said, the laser. I can't really go into details about it but they burn differently. I would assume that the dvd writers are built to burn at higher temperatures (maybe wrong) to store more data. I'm not sure but I think dvd drives "might" be able to read CDs and not the other way around. Kevin.

Parameter               DVD-R           CD-R Wavelength (Recording)  635-645 nm  775-795 nm Wavelength (Reading)    635-650 nm  770-830 nm Recording Power             6-12 mw     4-8 mw These are good links: STORAGE/CD-RECORDABLE/CD-REWRITABLE http://www.pctechguide.com/09cdr-rw.htm STORAGE/DVD http://www.pctechguide.com/10dvd.htm

Kevin is mostly correct. It's not that it's burning hotter though, it has to do with the wavelength of the laser. It's much narrower beam and therefore it burns narrower pits allowing for 4.7 gigs per disc as apposed to CD's which are 650-900 megs. And as Kevin stated, you can read CD-Rs on a DVD drive but you can't read DVD discs on a CD drive.