Got a Dell Latitude C840 at work running XP. It's got a Pentium 1.8 chip and 1 Gb memory. I am well overdue an upgrade, but frankly it is so good I am not shouting about an upgrade. No problem moving 25 Mb of data off a SQL server in to Excel...
Because it is so old, the COM port works. Integrated LAN. DVD burner.
The HD is 40Gb in mine - small but I am networked so no issue there. The graphics run at 1600 x 1200.
There's one here for a "buy it now" of £145
Dell C840 on ebay
P,S. Wi-fi is via a card, not internal. "Buy it now" for £6.00
ebay wifi PCMCIA card
Not used a C840, but have a C640 here, 2.2Ghz P4, 1G ram, 40G HDD. Decent enough, but being P4, too slow, too hot to run on lap, poor battery life, and this P4 era was a bad time for Dell reliability wise on there laptops (hence why so many Dell latitude system boards on ebay). Not sure why, lead free solder perhaps? Or simply the heat the things generate?
LOL my L400 is like that......just checked it now.....its red hot underneath and the cooling fan isnt even on
and yes the fan does work.......mind you its been on all day :-/
Check bios vers - seem to recall some Dell BIOSes from around 5yrs ago with errors related to fan control...
Its got the latest bios on it

First thing i did when i got it

It did have orig bios on it........
I know the fan works coz when you turn it on from cold fan comes on for about 10secs......then never seems to come again :-/