Hello,
I believe you should choose me for this project as I'm a keen .NET developer and have experience writing desktop applications and services.
My expertise primarily lies with back-end programming (so I'm fully capable of integrating with Windows system services), but I'm also able to write front-end software as you've requested.
I have experience with VPN connections and integrating with the Windows VPN system, along with connecting/disconnecting network drives - I can provide samples if you'd like.
Also, I'll support your software for as long as you need afterwards - bug fixes to the initial specification will be free, and future enhancements charged accordingly.
I've specified 21 days development because I want to get it right for you, and getting it right requires time (without any unexpected complications!). This time involves a prototyping phase as well, where you can verify I'm on the right track and happy with what I'm doing. I'll stay in touch with my progress, and keep you fully informed. Hopefully, you'll have a working solution sooner, but I don't want to over-promise and under-deliver.
You've posted this under the .NET category, so I'd be writing the software in C#, but I don't understand why you've also attached the PHP category.
Please don't hesitate to contact me via PM if you'd like me to clarify anything I've mentioned, and there are a few questions I have about your project before I'd be comfortable fully committing.
Kindest Regards,
Tom Spink