ZDNet has compared three Microsoft Windows siblings namely Windows XP, Vista and to be released Young kind on the block Windows 7 (Beta build) and has released the results. The results are interesting and favors Windows 7. It is interesting to see Windows 7 outperform even Windows XP with 1GB memory. The comparison does not cover systems with lesser memory where XP would run happily but its not known how windows 7 will perform, Its not worth comparing Vista in low memory system as it is known to trash a lot on low memory system.

Overall Rank is

1. Window 7 (Beta build)
2. Windows XP
3. Windows Vista

They have covered lots of areas like

1. Install OS – Time it takes to install the OS
2. Boot up – Average boot time to usable desktop
3. Shut down – Average shut down time
4. Move 100MB files – Move 100MB of JPEG files from one hard drive to another
5. Move 2.5GB files – Move 2.5GB of mixed size files (ranging from 1MB to 100MB) from one hard drive to another
6. Network transfer 100MB files – Move 100MB of JPEG files from test machine to NAS device
7. Network transfer 2.5GB files – Move 2.5GB of mixed size files (ranging from 1MB to 100MB) from test machine to NAS device
8. and more …

more here