Bibble4 will run OK on Vista, but I feel compelled to tell you to think very carefully about buying B4 with hopes of getting the "free" upgrade to B5. And "support" for B4, has been non-existent since last Summer. By that, I'm saying there have been no new camera profiles added, and none are forthcoming. No bug fixes or further updates of any kind will be released for B4, as stated by Bibble labs.
B5 is currently in what Bibble calls a "preview" stage, which means most of its features are missing or disabled, and it's so buggy I haven't been able to use it in any meaningful way. Who knows how long before a working version will be released, if ever? Bibble Labs right now, seems in dire straights, so caveat emptor. As much as I have enjoyed using B4, I can't recommend their products anymore.
I don't remember the exact price of ACDSee Pro 2.5, it might be a bit more than $100, but I really like it. I find it easier to manipulate the files in that than in Elements (5). I also have Bibble 4, but I like ACDSee better yet.