I'm amazed to see people speak about Vista as the Saint Graal of operating systems. Is it worth to upgrade? Many people will not ask the question and will jump to it with closed eyes. Take care!!!! You should better think twice before the upgrade (this is true for every software in fact). The article written by Randall C. Kennedy, Death match: Windows Vista versus XP, is interesting in drawing the most important reasons why you should stay with your XP version.
I'm also amazed upset to see that in 2008, a Microsoft Vista running on a 3 Ghz CPU with 2Gb of memory does not bring anything compared to an operating system from 1998 running a P3 350Mhz with 128Mb of memory. 10 years of serious hardware progress. Big regression on the software side.