[tex-live] Not so good experience with TL net install on windows.

[Karl Berry]

    Can I urge that a warning be added to this file, 

I added this text to http://tug.org/texlive/acquire.html and
ftp://tug.org/texlive/tlnet/2008/README and
ftp://tug.org/texlive/Images/test/README:

  If you have problems running TeX after installation, the first thing
  to check is your environment variables: settings that end up referencing
  other TeX installations (TeX Live or otherwise), can clearly cause
  trouble.

I also updated the /tldev -> /2008 links.  Thanks to everyone who
reported it.

karl