Javier, the colour architecture between v5.x and v6 or higher is quite different.
There are ways to set things up in a similar fashion.
Photoshop 5.x colour handling was a 'beta' that went public - the public should never have been forced to use this less than ideal system. Colour handling in v6 or higher is what users should have been offered from the start, but taken with hindsight I guess the way v5.x worked was a good way to introduce users to the new concept, even though it has many design flaws. It was an evolutionary step that is best left as fast as possible (v5.x colour handling).
So, you will need to tell the list all your colour settings under the file menu or RGB, CMYK, Grey and Profile Handling in v5.x.
Then we will need to know what preset colour setting you chose in v7 - probably the web defaults?
It is my guess that the RGB and or other working spaces and settings that you use in v5.x are not the same in v7.
More info on all this can be found at the link below, look for the links on colour settings at the Adobe and other sites:
http://members.ozemail.com.au/~binar...V_links.html#C
Regards,
Stephen Marsh.