Talon, seriously, you don't want Moulds, especially for the long term. He is on the decline and has had a series of continual nagging injuries over the past 3 years. All signs point to him being a has-been IMO. Walker on the other hand is the real deal. This would be his fifth season, he still has a lot of upside, and is taller and faster than Moulds. His injury last season was his only major injury, so there is no evidence that he would be more injury prone than the declining Moulds.
Personally, if the Owens to Dallas deal fell through, Walker was next on my list, but I wanted to avoid Moulds at all cost. I have followed him closely for the past three seasons (mainly because he always ended up on my fantasy football team) and he seems to not have "it" anymore.
Walker would be the perfect compliment to Reggie Brown, who has some major upside and can potentially become an elite WR in the future. Your best bet would be to have Walker and Brown as your one and two, and maybe a stop gap receiver like Peerless Price as your number 3...but stay away from Moulds at all cost.