I guess I'll just comment randomly.. with the disclaimer that all I know about these guys is their draft reports, havent played NCAA, havent seen em play.
Larry Fitz - Using the holly Bible that is madden, I have to say for a receiver to be great he needs a good QB and for a QB to be great he needs at least one very decent wide receiver. Case in point - Byron Leftwich struggling when Jimmy Smith was traded away and Reggie Williams was injured, thank god for Fred Taylor (in my franchise, of course

). So I expect he'll be great, just dont see a huge season ahead of him with Boldin taking probably more receptions and a barely servicably QB.
Sean Taylor - 2005 Roy, I agree.
Personally however, I would put my money on someone as far back as the fourth round being the rookie of the year -
http://www.steelers.com/news/index.cfm?cont_id=236998
Ok, so Domanick Davis isnt gonna happen two years in a row, but hey Tatum Bell is at Denver, and we know what happens in Denver
Not really looking at immediate impact, I think the best overall player is probably gonna prove to be Taylor, Gallery or Winslow. Even though all three could have explosive first seasons.. well maybe not Gallery, unless he starts flattening Simeon Rice and the like

He'll just be a big solid treetrunk on the left side that defensive ends will need to take a taxi to get around. Hehe, best thing he can do is make his weakside position sound ironic.
I just feel the need to tack on another question though, who do you guys feel was the best value/biggest steal pick in the first or second rounds? Things that come to my mind are the Steelers getting Big Ben aaaall the way at 11, Wilfork going to the Pats, Troupe to Titans, Colbert to Panthers and perphaps, Teddy Lehman to the Lions..