Fascinating... I'm using my Tualatin system since a year (I started in July 2017) and so far, I had absolutely no issues in terms of usability. Instead, I found pretty fun to search for workarounds and ways to push the performance to the maximum and see what's capable of doing considering the age of the machine. About SSE2, I haven't had any issue, but maybe that's because the programs I use just don't require it (as well as games, since I only play games from the 1990s to the early 2000s). However, I think I might have reached the maximum limit with the hardware I have, since I have overclocked the CPU to 1.5GHz with the FSB running at 148Mhz (the maximum stable frequency I got), as well as overclocking my current graphics card, an ATI Radeon X1950 Pro, gaining some extra performance thanks to it, compared to the Geforce 6800GT I had before. I tried to switch to a Radeon HD4670, but unfortunately either my motherboard is incompatible with it, or my PSU -a Corsair CX500M- is not powerful enough, or my card is defective, because XP just freezes at the boot screen when I put that card into the computer, so I'm just going to stick with the overclocked X1950 Pro for the time being.
However in future, I want to get a bigger PSU with more amps on the 5V and 12V rails, another SSD to replace the data HDD I have at the moment, and maybe look for Kingston 512MB PC133 CL2 modules, as I heard they are very overclocking friendly. I'm definitely going to stick with this old machine for a long time, it just works.
My Retro Daily Driver: Pentium !!!-S 1.7GHz | 2GB PC166 ECC SDRAM | Gecube Radeon X1950 Pro 256MB OC | 128GB Lite-On SSD + 500GB WD Blue SSD | Creative Sound Blaster Live! CT4620 | Windows XP Professional SP3