I have owned my Compaq Presario 7110US for a couple of years now, and have been a die hard Athlon fan since then. It is from the factory an Athlon 1.33 Thunderbird. After about a year, I started exploring the option of a brain transplant hoping to get some more juice out of my rig -- I had already invested in 1GB of PC2100 and didn't feel like purchasing a new board, cpu AND memory.
Being proprietary, I wasn't convinced I'd have any luck upgrading the CPU, but I decided to be my own guinea pig. After reading AnandTech's CPU cheatsheet, I determined that the fastest CPU that would match up with my 133/266FSB is a 2400+ which uses the Thoroughbred core. Lucky me, you can buy these all day long on eBay for around 60 bucks (thanks amdcpuseller). I upgraded the BIOS to the 3/28/2002 (latest) and waited for delivery of the new chip.
Results - success! The CPU fit perfectly and the system is noticeably faster. Here are the before/after Sandra numbers (before/after):
CPU Arithmetic - 7543/11266 - 49% gain
CPU Multimedia - 26168/38373 - 47% gain
Memory Bandwidth - 3190/3303 - 4%
As to be expected, very little memory performance gain, but look at the CPU boost! Just about 50% on the nose, which is right in line with the upgrade from my original 1.33 up to 1.99 of the 2400+.
The main reason I posted this is so that any other Presario owners will have something to go by in case they want to get a cheap speed boost. And while this isn't going to blow the doors off anyone's hot gaming rig, it makes me very happy. Another year of life (at least) for my AMD box.
In case you are interested, my Unreal Tourney 2003 benchmarks didn't change AT ALL, which means that CPU wasn't the benchmark - time to upgrade the GeForce2 card next!!!!