the only problem i could see is if you ever wanted to boot from a disk you may have to change your boot priority to the cd drive first and hard drive second in order to get it to work.
i don't see any issues other than that, just like rusting in peace suggested.
however just one thing of note: you can get a new (and faster) cd/dvd burner for as little as $10-15 oem. the new ones have sata connections. since you said you bought new components other than the burners, perhaps it is worthwhile to upgrade those as well (since its certainly cheap enough).