Hello Husk,
I will give you an unbiased advice. Both IE7 and shortly IE8 as well as Firefox 3 are safe and secure browsers if you care to make them safe and secure. That is when you care to learn about things that can go on inside a browser that can put you at risk. The biggest risk factor is sitting between the chair and keyboard, because he or she can do things with a browser that both put him/her and other people at risk.
There are things to make a browser more secure. For IE read this:
http://www.destroyadware.com/accounts/ctdp/iesettings/ Also be cautious with installing ActiveX and Browser Helper Objects. For Both IE and ff DrWeb's av link checker extensions is enhancing your safety, because you can check links before you go there. If you use to cleanse your browser tracks and temporary files after a browser session you are even more secure, I use IE cache cleaner and ClearProg. For Firefox I have ClearProg and ATF Cleaner.
As a tester for Firefox Minefield, the latest nightly builds, and a member of the MozillaZine webforum and contributing to Bugzilla's occasionally, I have a fair grasp as what goes under the hood of the Firefox browser. Firefox is secure, but there is a safer browser still and that is Firefox with the NoScript extension. This extension blocks flash, script, etc. on pages and part of pages until you need the functionality and partially unblock the functionality you need. NoScript protected every time a new vulnerability was found for Firefox, and even for those that haven't been found up. Because with extensions like Adblock Plus and NoScript and TrackMeNot etc. the browser trackers and profilers could be quite hampered, also think of an add-on like Stealther, that formed one of the reasons for Google to launch and promote their Google Chrome browser. This was also one of the reasons web developers protested against NoScript being added to the browser code by default.
It is true that IE starts up faster, because explorer is part of the OS and parts of it already start up while the OS is starting up, Firefox 3 is much faster already as it ever was. I like to assure you that Firefox is one of the more secure browsers, IE is also secure if you do not run it as it comes out of the box, but alas that is almost with every program for the windows platform these days, and the average user is unaware of this fact. Another important thing is the browser is as secure as the things you do with it, going to unsafe sites and downloading risky things puts you at risk, just like running down a back-alley where the cameras are off,
polonus