USA IP address for VPN Client while travelling out USA

I am a contractor and I work mostly from home. My current client is in USA but sometimes I have to fly to eastern europe at another client site for couple of days. When I am in Eastern Europe, I still want to be able to show USA IP address when I connect through Cisco VPN client to my USA customer's network. I thought about getting another VPN service which will give me USA IP address. Is that the best way to do it? When I tried one of the free VPN service and looked at the VPN client connection log when I connected to the USA client's network, it showed entries for both my Easter Europe's wireless ethernet card IP which is outside USA obviously and another IP through the free VPN. In that case, my USA client will know that I am not in USA.

What other ways can I achieve this? I tried gotomypc by connecting to my USA server then using VPN client from there but performance is too slow.