Any good, reliable machine with a minimum of 3 USB ports. I use ThinkPads. Here's a great source:
For ThinkPad lovers (the only laptop I’ve ever had; I’m currently on my 5th), do some price checking and then call this guy to see what he has:
Robert (Bob) C. Bogutsky
5064 Overcrest Drive
Kannapolis, NC 28081 USA
Telephone (Home) 704 785-9276
Primary Email ID: email@example.com
Facsimile: 704 782-4911
Mobile: 704 258-3287
He's a retired IBMer, who has great (legitimate) sources of new and slightly used ThinkPads, all with Lenovo warranties which can and should be verified with Lenovo prior to buying, which he upgrades and sells a few on eBay but mostly privately since that gives him the ability to work with the potential buyer and suggest units and alternatives. I am using a T61 now that I bought from him. You get a lot more for your money with Bob than anywhere else. Mine came with only 8 months left on the warranty, so I bought a 2-year extended warranty from Lenovo for $129.
You can't go wrong with Bob. He's terrific and so knowledgeable.