Here is the simple truth:

A Pentium 3 with Windows 2K Professional will run wireless internet and Microsoft Office (Word, Excel, PowerPoint) "at the same speed" as a Pentium 4, M or even the Core Duo.  Additionally, for the user (you) Windows 2K will do everything that XP or Vista does to operate your programs. NFS notebooks come with Windows 2K or XP, see description for each notebook.

So don't worry, a Pentium 3 will run all your programs and the Internet just fine.