I've tested Win7 in Beta and what turned out to be the RTM. On a dual core with 4 GB of RAM its a fine OS. Faster and much more reliable than Visaster. It did a number of things I was impressed with but there is no compelling reason to run it. That's at work or at home.
I try to install as little software as possible on a computer's OS to keep the running speed to a maximum. In Windows there are limited things that can be done like killing the taskbar tray, shutting off unneeded processes, etc. Even killing the Explorer shell can give you a little speed boost of about 1% and about 15 to 20 Megabytes of more RAM space in XP Pro. Most applications using Win32 API calls will still draw windows and do the Windows Form library functions without having to run a full Explorer desktop.
I find that Ubuntu 9.04 runs the exact same applications as XP I need at work and at home for 85% of my work. Word Processor/office suite, a web browser and email client application. For those situations where I HAVE to run Windows, I'll run XP Pro in a VM hosted on Ubuntu. Its about as fast as Win7 without a VM on the same hardware.
The complaint I have with Windows OS that Linux addresses to a certain extent, is that I can strip out or NOT install big chunks of software that is more rightly defined as application layer software instead of the bloat the has driven Windows into the ground performance-wise.
Considering the speed increases in the hardware, the operating systems ought to be running 5 to 10 times faster than they do. Mr Kingsley-Hughes timings on the install/upgrades confirms to me that the Win7 operating system is too damn fat. (check out his column over at ZDNET.COM yesterday)
Years ago I did tests comparing an application suite software our company wrote running on Windows 2000 Workstation/Pro SP4 and XP Pro SP1 on the the exact same hardware, same RAM, hard drive etc. Win XP Pro ran the software 20% faster than Win2K.
A similar test I've done running our current application on Windows XP Pro and Win7 Beta on the exact same hardware revealed that XP Pro was faster by 5%! What happened?
I went through looking at what processes were running on the 2 systems. I tried to optimize the running processes in Win 7 to approximate what was running in XP Pro. I did speed up Win7 a bit but not enough to be statistically significant. Win7 was still slower than XP Pro. Both tests were done again on the exact same machine with 4GB of RAM, both Windows OS versions were 32 bit and the video and network drivers were Microsoft's device drivers. XP Pro was running SP3 and Win7 was running the Beta.
If you open the Services windows in both XP Pro and Win7 and compare, there are approximately 3 times as many services running in Win7. A lot of them do arcane tasks that have little service for data display or word processor-like applications. The trick is to figure out what can be shut-off.
Its obvious that I will have to repeat the test again once Win7 comes out. I was very surprised by the results. I expected Win7 to blow past XP Pro.