That's Amore in Highbury is nice - make sure if you go there you order one of their speciality dessert pizzas to share - yummmmy! Think sweetened pizza based with chopped up crunchie bar, strawberries and fresh cream for example! They also do nice steaks, fish, and have a daily specials board to choose from. Good choice of wines too.
Alternatively if you are not in a hurry there is Belmondos on GJR - east side of junction with NER. Nice food, but bit slow last time we went there.
I'm told that the absolute best steaks anywhere in Adelaide are at the Alphuette - think it's Wakefield Road on the East side, just after you've crossed the Parkland heading into the CBD. V pricey though, depends if it's a very special birthday!
Remember not to go too late - went to Ned Kelly's in North Adelaide recently and by the time we were ready for desserts and coffee (we sat down at 7:30 and went straight into steaks to save ourself for desserts) the coffee machine had been turned off, and the kitchen staff had gone home! Think it must have been about 9:30pm!!
Oh, and if you like Chinese, the Raffles Room opposite TTG Hotel is nice - does crispy duck and pancakes - yum - or the Ruby Raja is nice to eat in for Indian. Never tried the food at the Fox and Firkin but that's supposed to be nice too, if a little more casual.
I do like my food, me!!!