Having watched a huge amount of Arsenal games, (as noted on www.arsenal-america.com , little plug for the site) I have come to the opinion that Seaman really is past it and should just step down at the end of the year, why I hear you say? because he has slow feet, he just can't seem to get moving as quickly as he should be. Taylor on the other hand is quicker but not as confident, he does not "own" his penalty area, however this will come with time and more games under his belt. He was really good against Chelsea getting down quickly etc, although he did get away with some things, however time will bring experiance.
Taylor did stand up and look great against Chelsea but Seaman still has a year left. He does get injured more often but his experience and command of the defense is irreplaceable(is that a word?). I dont kniow if Taylor is the future. At times he looks confident and quick but he still has problems communicating with the defense. I did like the fact that when Chelsea scored he got up and chewed the defense a new one. That shows that he is trying to gain that command. I guess time will tell.
Seaman has a good year or two left. Taylor was great against Chelsea, but he wasn't very good against Everton, IMO, and was absolutely dismal against Blackburn. When I saw both of their goals scored against him, the only thing I could think was, "Seaman would've caught that." That said, I do believe that Taylor is going to be great-- he just needs more matches and better communication with his defenders. (He seemd to be having serious trouble with Cygan during the Blackburn match, for example.)