Forcing index.php (WAS: Issues Removing index.php)

[eluser]Jonathan Ledbetter[/eluser]
Thanks to all who have helped with this problem, but I think I'll contact HostMonster and see if they have any light they can shed on the situation.

In the meantime, I'd like to force "index.php" into all my URLs using .htaccess, and I'm not sure how to do it.

BEHAVIOR:
I'd like to go from this:

http://www.jandbledbetter.com/
http://www.jandbledbetter.com/other/index/123/abc

to:

http://www.jandbledbetter.com/index.php
http://www.jandbledbetter.com/index.php/other/index/123/abc

However, I would like "index.php" to be added only when it is not present. Therefore:

http://www.jandbledbetter.com/index.php
http://www.jandbledbetter.com/index.php/...ex/123/abc

should not become:

http://www.jandbledbetter.com/index.php/index.php
http://www.jandbledbetter.com/index.php/index.php/other/index/123/abc

Does anyone have any ideas? Like I said, I have no idea what I'm doing with regard to my .htaccess files. I'd be really thankful, and I'd credit you in my colophon when my site finally gets up and running.

Thanks in advance! I'll try looking on the forums when I get the chance as well.