Security issues

[luis]

Hi,
1 - I work in a enterprise that already have an intranet working arround all the contry with many agencies conected trough internet
2 - there is a router in each agency the allows the conection to the intranet
3 - I want to install a  [b]http server [/b] (IIS) in one of these computers in order to create a PHP/MYSQL based application then can be accessed from anywhere in the intranet.

The  question is:

[b]Are there any [size=10pt]secutity issues[/size] because of it???[/b]I mean is it possible to someone to atack the intranet just because there is anoter [b]http server [/b] working in it??

Thanks in advance...