I do not see the connection between IE-7 and Windows Vista.
If you are having troubles with IE, you should post details in an IE
newsgroup and the experts there may be able to help.
As for upgrading...
You have not given any details of your system, hardware and software needs
and what you need from Vista.
Generally it is a bad idea to upgrade an operating system simply because
there is a new version.
Only upgrade when you have determined there will be an appropriate benefit
for you.
This applies to almost any type of upgrade from any source, not just
Microsoft.
Windows XP will be supported by Microsoft for several more years.
Most typical users have no need to upgrade to Vista and should wait until
they also need a new computer.