I'm not sure about web based email like GMail, but as you said you got it to work in XP then I must assume it is possible to do that in Win 7.
Look in the Start Menu for "Default Programs" in the right hand column.
You're going to have to explore this, but at first glance the best option would seem to be the top one, "Set your default programs". If GMail lists, then set that as default.
If that fails, try the bottom option, "Set Program Access and Computer Defaults". You will need to click the double chevrons for more details on each.
See if any of those work for you.
I recently moved from XP to Windows 7. I use web mail (Gmail). When I was using XP and I wanted to e-mail a photo I right clicked on the photo, selected "send to" then selected "mail recipient" and it opened my gmail program and photo was ready for sending. The same procedure now takes me to Windows Live and I do not wish to use Windows Live. (Nothing personal, just my preference).
I know I can select "attach a file" in gmail but it seemed much simpler using the the right click method.
Is there a way I can use gmail instead of Windows Live?
As an aside, I might add I am old dog. Don't learn new tricks like I used to. That's why, after all these years, I am still a Newbie. I don't always appreciate all of the "stuff" they include that I will never use. I had my new computer built locally, at a favorable price, and one of the advantages is there is a minimum of bloatware.