The only software that had a conflict was my Symantec Anti-virus 1.5.1 that had a lot of errors after the install, and that a Live Update did not fix.

When I upgraded back about 10.2, I had to buy a new anti-virus software item, and then my Mac went vulnerable for some time before the upgrade appeared

That's what it's like running windows: criminal gangs that produce viruses and spyware are way ahead of the anti-virus people

Silicon Image eSATA drivers, SilverKeeper, SmartScroll, Sprint SmartView, SMS Mac, Sophos Anti-Virus, Split&Concat, Squeezecenter, Sticky Windows, TivoDesktop, Toontown Online, Vonage Companion, WD Anwhere Backup, WideMail, Winclone, WindowShadeX, X-Lite, Xmarks for Safari, Xsan, XScreenSaver, Zend Server, ZumoDrive

I can't comment on any new features, but it works as it's supposed to.

10.5.8 was still there and everything worked as if nothing had ever happened

I bought this program from the apple store to install on my 20'' iMac, previously running os x 10.4, & after installing it and updating everything, it worked as if brand new