Changing Gmail account on G1

[short of infinity]

How do I modify my G1 to use a different Gmail account? If I did this, would I loose the tracking of my purchased apps from the market or are they transferrable? For example, if I need to reset my phone, Google tracks which apps I have already purchased so that I can re-download them. Will I loose this capability if I use a different Gmail account?
Thanks in advance

[Nelly G]

You can remove the Google account details on your phone by going to:

Menu -> Settings -> Applications -> Manage applications... Then from here do the following three in order:
Google Mail -> Clear data
Google Mail Storage -> Clear data
Google Apps -> Clear data

Then run the GMail app and it will ask you for your login details again.

Some phones need to be turned off and on again.

Your purchases, unfortunately, are associated to the Google account that you purchased the apps with originally. There is no way to transfer them. However, if I recall correctly, the purchased apps remain on the phone. I don't know if you will be able to update your purchased apps or not either.