I disagree about gemming for hit. I've read for a long time that gemming for hit when you need a bit is fine. Gemming for crit, however, no, especially for an arcane mage. I'd gem sp/haste in those yellow spots in the legs. Icewalker is fine if you need the hit, but you'll probably start getting more hit in your gear, at which point you can use runspeed enchant. You can get by with 8% hit as arcane as long as you have a boomkin/spriest in your raids (I understand if you can't count on that, I couldn't for a long time). I wanted to give up my t9 helm for that cowl in ToC5, but I played fire too often back then to do it.
Here is the hood he's talking about:
http://www.wowhead.com/?item=47692
I'm with Anobix, though, get those two trinkets he mentioned. I didn't break my 4pc until I got 2pc T10. Anyway, I loaded your toon into Rawr and it shows a dps loss for trading for that hood. The setup assumes a lot of buffs you might not be getting, so I don't know how correct that would be. The only upgrades Rawr shows are the 245 hood, the T10 and a hood from ICC10 that's not even available yet. Rawr also prefers a different gemming for your robe: sp/crit, sp/haste and sp. Straight sp on wrists. Belt sp/haste and sp. Again, my setup assumes a lot of buffs that you might not have, so install it and run it yourself to help with gemming and upgrades. :)