IE7 does have better security. It has a phishing checker which checks if the web site you are going to is genuine or not.
As you do banking online this may be very useful.
It also has tabbed browsing, which allows you to open two or more web pages in the same browser window.
Note there is also a browser called Firefox which is free and many people prefer it over IE6 or IE7.
Firefox is more secure than IE6 or IE7 as people are less likely to write viruses for Firefox than for IE6 or IE7.
You can get Firefox from here
http://www.mozilla-europe.org/en/products/fire fox/