Backtrack 4, Nmap 5.20 and upgrade quetion

[Greuceanu]

Hello!

Running nmap -O to scan my own computer i noticed it can't detect that it runs Windows 7. (shows up as Vista or Server 2008)
So i assumed that nmap is a bit older. Backtrack's Nmap is 5.00, nmap site shows 5.20 to be the latest version.
So i procedeed in running apt-get upgrade and got the following lines:

The following packages have been kept back:
nmap openvas-client openvas-libraries openvas-menu

So i have a couple of questions, if you guys can help me:

1. Why are those packages beeing kept back?
2. Is there a way to unkeep them back?
3. Should i manually install nmap 5.20 or wait for it be upgrade through the repository?

Thank you!

[Reaper45]

Just issue the commands apt-get update && apt-get install nmap, and it shall work fine.

[Greuceanu]

Thanks for the tip!
It updated to 5.21, no problem.

But running a -O scan now no longer detects that is even a windows machine (used to say vista or 2008 server ... it actually is win 7). It now guesses:
Running (JUST GUESSING) : Apple Mac OS X 10.5.X (95%), DVTel embedded (87%), BlueArc embedded (87%)
Aggressive OS guesses: Apple Mac OS X 10.5.5 (Leopard) (95%), DVTel DVT-9540DW network camera (87%), BlueArc Titan 2100 NAS device (87%)

Weird!