I don't think the Arsenal - Barca games will be that close, Wenger as stubborn as he is will one again try and play Barcelona at their own game and get humilated.
Last year Arsenal tried this and were battered at the Emirates by an arguably worse Barca team, and would have been about 5 down in the 1st half if not for a misfiring Ibra, David Villa won't give them the let offs Ibra did.
They then got beaten at the Nou Camp with Vermalean defending, he might not even make this game.Messi had a field day with Vermalean in defence what is he going to do to Laurent Koscielny who gets beaten by the likes of Diouf.
Arsenal need to do what brought them goals at the Emirates, use pace on the wings as Barca can be suspect defending here with their full backs being so attacking and also crosses into the box for Bendtner and Chamahk to head, Barca are not that strong in the air.
As for the other ties.
Internazionale - Bayern München = Bayern München
Inter are not anywhere near as good as last season with Rafa in charge, i think they will slip up here against a good but not great Bayern team.
Valencia CF - Schalke = Schalke 04
Valencia are a good team on their day, but so inconsistent, Schalke are not bad either and i think their decent attacking players will be too much for Valencia.
AC Milan - Tottenham Hotspur = Tottenham Hotspur
I expect high scoring games from both, but in the end i think Spurs pace will be too much for Milan's old defence, plus i would love to see Spurs vs Barca for all those idiots who think Bale is as good as Messi or would make it in the Barcelona team.
AS Roma - Shaktar Donetsk = AS Roma
Roma because they are just a better team with better players, wouldn't expect either of these teams to make it past the quarters though.
Olympique Lyon - Real Madrid = Real Madrid
Lyon won't knock Real out this time around, despite the 5-0 at Barca Real are fantastic under Jose, Ronaldo is better then last season, if i had to choose a team to win the Champions league they would be it.
Arsenal - Barcelona = Barcelona
Olympique Marseille - Manchester United = Manchester United
This United side are poor by their standards but United always tend to pick up in the 2nd half of the season, they will have too much for Marsielle, who are a good team especially in attack, but this is a step too far.
FC Copenhagen - Chelsea = Chelsea
Chelsea are in poor form with nothing to suggest a turnaround any time soon and Copenhagen are being overlooked, they are a decent team and did well in their group. I could see them getting a draw from Chelsea at home, but Chelsea will have too much for them at Stamford Bridge. After Barca and Real i would consider Chelsea favourites.