We need a vpn client that support openvpn and pptp protocol.
We need openvpn to use key,crt files and username/password.
We need a simple ping and download test to recommend the best server to use.
Openvpn proxy support (client can use proxy)
Openvpn fail on default port (if ISP block port in firewall) chose next port automated.
Disable traffic if connect failed.
Simple install.
Download/Upload speed.
We need gui (we got the design done png files) and support for all windows version 32 and 64 bits. (windows vista/7/8)
I have significant experience in writing VPN clients, using IPSec and PPTP in Windows making use of hte Windows RAS API and interfacing with the OpenVPN Client over sockets. crt files/username and password are not an issue neither are bandwidth tests.
I have built software cross compatible with 32bit and 64bit in a single installer with TAP/TUN Driver installation in a single package.
I would propose C# for this however for PPTP I do have a code base for a single .exe with no dependancies file written in MFC/C++.
A copy of the png file would be userful to see whether it is a fully skinned application or partial skin.