Hi,
I have the full Professional version of TT. To be honest I never try it with the old browsers. Don't forget that IE6 is from 2002 and IE7 is from 2007 if I am correct.
I will try to find an old computer and test Magento with old browsers and I will let you know. Give me few days and I will tell you.
You can try to upgrade IE 7 to IE8 if you are using XP. Keep in mind that XP will be supporter until 31/12/2013.
I'll give you an advice. If you will buy a new computer DO NOT buy it with Windows 8, prefer Windows 7, they will be supporter until 2019 and meanwhile the Windows 9 will come out and hopefully they will be the new XP :)
IMO XP was the best operator system ever, then Windows 7.
If you noticed, Microsoft is making a good and a bad operator system
XP- Good
Vista- Bad
Win 7 -Good
Win8- Bad
Anyway, hopefully at the end of the week I will find a pc with IE6 and IE7 and I will let you know how they respond to Magento.