Hi,
Will this be your only computer (ie will it replace an existing desktop) or supplement?
Where are you based? (just to find out local suppliers)
At my last job the minimum spec for laptops was as follows:
1GHz mobile CPU, 512Mb RAM, Windows 2000 Pro or XP Pro, 56K modem, 10/100 LAN, CD-RW/DVD-ROM combo drive, min 2 USB ports, external VGA and PS/2 ports, slot for kensington security cable.
This should cope with anything - some people opted for the subnotebook type with smaller screen and detachable drives, while others opted for the full desktop replacement with everything and the kitchen sink thrown in.
Optional items were: floppy drive (normally bought an external USB device where needed), carry case, security cable if they were to be used in dodgy locations.
This was a year ago however, so things may have moved on since then.
John