I had the same problem when I tried Windows 7.
The cause is Micro$oft. In window$ 7, you are not allowed to run java without giving special permission.
The stupid thing is, that if you even try to find the file (javaw.exe) window$ pretends it cannot find it, even
if you just installed it. The reason is that Micro$oft hates java, because you don't need window$ to run it.
(if you ask me, you don't need window$ for anything, you will live longer if you don't use it).
When you find it, you have to change the permissions to run the program.
Fortunately, the solution is described in the pskmail FAQ at:
PS: I hope you did not have to pay for this completely useless piece of software (window$7).
PPSS: It is very easy to put Linux on the netbook....