clean a cd drive is easy and fun, a learning experience
it is the first thing i would do, open the drive and do a direct clean over the lens, using cotton and a very small amount of alcohol, there is many videos explaining how to do it, there was another post i did some months ago but maybe it doesn't exist anymore
if this procedure doesn't help, replace the ide cables could help alot
also check if the ide drives are set as master and slave respectively, this will be written over the drive itself, you will probably need to remove them to look properly at this, one should be master and the other slave, the one set as master goes in the last connector if the ide cable, the slave in the second and the other side of the cable in the motherboard, verify that all connectors are completely inserted in the sockets
as i mentioned, no idea why but sony drives are the some of the worst options around, lately their quality has improved because in 2005-2008...

if the drives are just saying bye, you don't need a new pc, only replace one of the drives with a new dvd burner, as easy as connect two cables and put 4 screws
lots of users recommend samsung and lg(lg i use, always) but the most recommended is lite-on and plextor drives
i wouldn't get a bluray drive, linux doesn't support it yet, only windows and ps3 works really with it, that includes osx, not working yet there neither
another option is go for external drives, depending on the usage, you could be a good candidate to use external drives, if you are like me and use very rarely cds and dvds it is a good option, i have a lg external drive and works well to install livecds and other os too
i only connect it when i need it and that is maybe each month or two, my pc usage is not oriented to media content stored on cd or dvd discs but that is my small world, each one decides what is best for his requirements