Let the hive mind of Engadget get that for you.
"As someone who doesn't reside in the USA, I was wondering what would be the best way to get internet for my computer in the US for a couple of weeks? If it were Europe I know I'd look for some prepaid data. Is there anything similar offered by American carriers? A MiFi or a data SIM that I can tether from would work, but I'm trying to maintain a tight budget. Help!"
I had to double take.
Windows Mobile 5.0 Premium?
In WinMob 03 days, that pretty much meant it includes L2TP/IPsec VPN support. But I think 5.0 includes that by default.