There are a surprising numbers of free utilities that work with Windows Vista.
My faves are FoxIt Reader, a fast & free replacement for Adobe Reader; NotePad2, a smart NotePad replacement for programmers that color-codes text based on file extension; and Ad-Aware SE Personal, which scans for spyware & other such nasties.
Thus far, every PDF that I've opened with FoxIt has displayed just fine, without the long loading times (and frequent bloated updates) of Acrobat. The only downside is that sometimes IE doesn't recognize that FoxIt can open a PDF, and presents the dumb "Windows cannot open..." message.
NotePad2 is a must for programmers (like me) who sometimes still print out listings, especially for long or complex programs. It uses the file extension to apply the appropriate color scheme for that file type. The source code is available for the curious (or compulsive tweaker) and I've even had the program running under Linux using the wine Windows emulator.
Next is the excellent Ad-Aware which protects from spyware, much more effectively than the native Windows Defender - even after this morning's Defender definition update, Ad-Aware found five tracking cookies & allowed for their easy quarantine & subsequent removal.
My final fave is a VB6 program that I wrote to print the screen, and what do you know? It also works with Vista. Imagine that.