since in linux we cant have internet explorer, then have to use konqueror, mozilla/firefox, opera, and some that i dont know of.

which browser is safe and approvide to be save for sensitive browsing such as for ebanking , and sending credit cards information to legit sites?

All of them. Whether the institution has written their system to be all browser compatible is another matter. If push comes to shove and you need it and they only take IE, use Wine to install IE.

if it said higher then netscape 4.5 will mozilla do the job?

I think Mozilla shows up as Netscape 6 (afaik). Konqueror, can pretend to be whatever browser you need for various sites.

For example, in Konqueror:
Click Settings --> Configure Konqueror
Click Browser Identification
In the "Site Specific Identification" box, click New
In the "When Browsing the Following Site:" box, type in the url of the site you wish to visit
Select a browser in the "Use the Following Identification" combo box - I have KDE 3.2 and I can say Konqueror is Internet Explorer 6 under Windows XP, or any one of a number of browsers.

If your version of KDE is less than 3.2, it may be that you can only be IE5.5, but have a go. You can even be Safari on OS X.

most browser can pretend to be other browser expect IE
opera can be set so it will said to a webserver that it is ie6
but with this is it safe interms of security?

All that happens is that the browser identifies it self as something else. What are your security concerns? As long as you follow normal security procedures, you will be fine. It only identifies itself as IE, it doesn't take on the other attributes of IE - you are still running something else on Linux.

In my experience spoofing will work on some sites and not others. For example I used the be able to access the Royal Bank of Scotland from Konqueror 3.0 but when I upgraded to 3.1.4 I could not get in. However, Mozilla 1.4 would let my get in but none of the menus would work and rendered the site useless.

On the other hand I have no problems with Nationwide or ING Direct.

I use Netcscape 7 because of its 128-bit Encryption, and Opera for general browsing.