The place where mages really shine is, in fact, not 5v5, but 3v3 where they run with a rogue and a priest (or druid - seems to work good as well). The only bracket where a mage can be fire is in 5s, but it isn't recommended, as you'll get slapped within secs, resilience or not.
That being said, does as mentioned above, farm for s1 and all the other honor gear, specc 17/0/44 (I know you didn't wanted to hear this, but I have to say it :P), realise that mages are mostly brought for control and that shatter combos are only brought into play when the rogue has prepared an opponent for you to blast. Then you can go PEW PEW.
And btw - keep you spellfire for when you want to do PvE-content, since raiding as frost = CRAP (or at least, raiding as fire is ten times better). The single most important stat for PvP is resilience, and all the crafted stuff has 0 of it, so it sucks for PvP! At least on my server (talnivarr, EU) above 1500 rating, it's resilience>300 or bust!
EDIT: the talent link finally loaded (dunno why, but I couldn't open it before), and I've gotta say, that while this might work in the low ratings, anyone with some resillience and a healer will do /lol at you - fire is a dead PvP specc since fire was introduced. You gotta remember, that when you run with a rogue, you are the only visiable target, so you'll be the one getting attacked. When people notice you are fire, they'll keep pounding on you - and a warrior won't need to pound you for a long time before you go down.
Edited, Jan 7th 2008 3:16pm by krqllebqlle