Alice- I also have to blowdry and straighten my hair everyday unless I wewant to look like a bush!
I really wouldnt want to chemically straighten my hair.. its alot of money for a big risk in my opinion.
Just stick to you straightners, and although this CAN dry out your hair, making it frizzy and/or brittle.... like 5029 said as long as you use a treatment it's fine.
I use John Friedas Hair Serum. You just run a small amount through your hair while still wet, and then style as usual. It really does leave it looking and feeling smooth and shiny (do I sound like an advert here?? :oD)
It is quite expensive at �6 a bottle, but it lasts ages.
Hope ive helped!