Another alternitive is an older model IBM Thinkpad -- they have *Intel's* wireless adapters built-in -- Intel's wireless adaptors are the most painless wireless adapters in existence since they are supported by an open-source driver that is included with the base kernel distro. Almost all others require all sorts of fun and games to get working under Linux.
I think that Thinkpad W-series is the best of Linux laptops, it is still sad that they are using ati card instead of nvidia.
My work computer is fujitsu-siemens celsius H250, it is very good but build quality is poor ..
Usually this kind of laptops can take up to 8GB of main memory.
-- Eero