Another option is to map the network drive to Z: (or whatever). The caution here is that different individuals in your company may have their network drives mapped differently (or not at all). If you have a good IT department they should have already standardized this and it shouldn't be an issue. Regardless, if this is for scripts you are only running on your computer there shouldn't be an issue.
An additional word of caution on using a Mapped Network drive, the file that you are testing for are on a web server. They may not be on a server that supports MS Windows Mapping access. At my company, Linux is used for the web servers, without any Samba(Windows file services emulator) installed. So the method I previously specified is what I had to use.