[citation][nom]Haserath[/nom]XP is still better than 7 for netbooks. 7 uses 1.5GB just sitting on the desktop, that is way too much for a netbook.Linux would be better than both for a netbook anyway.[/citation]
Learn how its memory management works...
The memory consumption reported in Task manager includes cache + active + inactive memory.
While it shows 1.5GB in use, the actual "Active" memory is far less. Cache memory is 85 - 90% of the memory useage on a clean install.
If you dont understand the difference between cache, active, inactive and free memory, see google.
That said, I've used windows 7 on an D150 Acer netbook for a while and it performs to the expected level, a little slower than XP but not much, and in some operations it is actually faster. However, as always, YMMV.
As to Ubuntu on a netbook, thats a fine OS to use.