There would be a benefit in speed, but depends on what you would use the computer for.
What memory do you use? There were 100 and 133MHz FSB versions of the 1400 Athlon; Thunderbird "B" and "C" respectively. If you run the B core you'll need to to upgrade the RAM. In terms of power consumption, beleive it or not but the "Palomino" core version of the XP2100+ would use roughly the same amount. It uses a lower core voltage as well as smaller die size.
Also, if you intend to play some modern games then you can practically guarantee that using your existing card, say a Geforce 4 MX, would give virtually zilch improvement; you would need to match that CPU with a fast video card like a Radeon 9600XT or an older, but still gold, Geforce 4 Ti 4200.
' ">http://www20.tomshardware.com/...09/images/image005.gif to see how the GF4 Ti cards scale with such upgrades.
If you can get to a trade fair you can often pick up deals whereby the seller chucks in the CPU, cooler and bang up-to-date board for a good price. You get nice things as well like USB 2.0. I know this is a bit off-topic but I'd weigh this option up against your intended purchase, especially as folks having been buying "Barton" cores (e.g. XP 2500+) and over-clocking them like crazy.
. AMD CPU Data: http://www.tomshardware.com/20.../amd...ult/page23.html
. Belarc Advisor: http://www.belarc.com/free_download.html
. GPU Comparison for Laptops: <a href="http://www.notebookche