It really depends on the controller card. Most inexpensive cards are lower performance than the IDE from the mainboard but higher end cards can actually surpass mainboard performance. Obviously the more they cost the mor eoptions you have, like flashing BIOS and such. Simply put, you get what you pay for.
I would in your case get the cheapest controller card possible and throw an optical on it.
Some disagree that using controller cards and preferring them to have the HDD is better(I saw this before in many posts here at cdfreaks), but from personal experience and doing benchmark tests I see this is untrue. I had a promise card however that performed better than the IDE on the mainboard. So you never know, do your research first.