Hi Dean,
That may work - different browsers work differently. But then you'd be stuck using Firefox because of this issue. The option I proposed (if it works) should allow you to use any browser or program - giving you more choices (as well as backups in case you have trouble with one browser). I mainly use IE9 beta (I do NOT recommend a beta product unless you really know what you're doing - in your case, I would use IE8), but I also have Chrome and Firefox installed in case I have a problem with IE or a website that has problems with certain browsers and not with others.
I would select the solution that gave me the most options and alternatives as well as solving the underlying problem - but that's only my personal opinion. If your theory works and you feel comfortable with only one browser and that it is that browser, then the problem is solved as far as you are concerned and that's what matters. I just checked Firefox and it does indeed have an option to choose Gmail as the default for email - something I can't do in IE though I didn't check Chrome (and while I'm sure it will work when clicking on an email on a webpage, I'm not completely certain it will work if you try to send email from Microsoft Word or open an e-mail attachment or link in Word (or other programs like that) - but I guess you'll find out). In theory at least (I have not tried or tested it myself so no guarantees), the option I provided would work in those other cases (according to the marketing hoopla that they say on the website which I usually take with a grain of salt).
The choice, of course, is yours. We all have our personal preferences. I, for example, have several e-mail accounts and account providers (including an essentially unlimited number from my private domain) that I use for different purposes. One for example I use for any online registratations which essentially keeps SPAM isolated to that one account and my others remain reasonably clear (not totally, but it certainly helps a lot). Despite 6 different providers (all but one are free), I do not have a gmail account - not because I have a problem with g-mail (I don't), but because I just never chose to give them a try and don't need another provider at this point. Plus I prefer to use e-mail programs rather than browser versions (since they typically have more options and I can control my accounts better and don't need to worry about how much space I'm using storing them online) - though I do on occasion use a browser to access one or another of the accounts and it may be possible to access g-mail with an e-mail program (at least one of the 4 I have installed) for all I know.
In any event, if I can provide any assistance, feel free to post and I'll do whatever I can to help - but at the moment, you seem to be carrying the ball so just let me know if there's anything I can do.
Good luck!