Need help for private browsing?

Hello,

I want to secure internet browsing and emails communication of my two executive users in my company. Currently they are behind ISA (secureNAT). I want their every communication over internet to be encrypted to secure them from every kind of attack/hack.

I would like to use VPN for this, should I use Windows based VPN service to protect them? If yes what is the best VPN service?

Or Any hardware based VPN service?

Please guide whats best solution should I choose?

Thanks