Do you mean PM 24.7.2 (which was the last true XP version) or 26.5.0 (which was the last official XP version but aimed at Atom processors)? In either case I don't blame you for not enjoying those older versions; if I'm not mistaken both were forks of Firefox 24ESR (the code of which was starting to get VERY dated by the time 26.5.0 was released). I don't think the Pale Moon team began forking from 38ESR until version 27 came out. Pale Moon and its forks are an odd beast...though the code is forked mainly from 38ESR there are bits of code from older versions that give it compatibility with some older addons (like an older FF28-compatible QuickJava version which I've confirmed works in Mypal and Michael Walden's Foxscape theme; a fork of the latter was released for Pale Moon, but if I'm not mistaken the last version for FF28 also works with no known bugs/glitches).
By XP standards that is some very solid hardware. I'm not sure what you're using to watch action movies, but for multimedia in general I've gotten by on a combination of VLC 1.1.11 & Winamp 2.79 for several years now. Winamp delivers flawless MP3/WAV playback and VLC has been able to handle virtually every format I've thrown at it. It even does high-definition video flawlessly too. I'm thinking about getting a newer PC, perhaps something from the Sandy Bridge/Ivy Bridge era, and seeing how it does with XP. In the meantime this P4 is still doing what I need it to do--I'm not ready to put the old dog down just yet.
Don't recall for sure, but I think I had this one ~ https://www.filehorse.com/download-pale-moon-32/24282/. I remember doing a Google search for 'last Pale Moon for Windows XP download', and that one at filehorse came up.
Are you having any problem with sites opening a plethora of tabs or windows on Mypal? This one site I favor for movies and TV shows keeps nailing me with five to ten of them each time I click on anything there. I have no clue what I'm using to watch movies. I think I'm 'streaming' them onsite. I do have VLC, Daum, and some other stuff, but not sure if any of that is in play in the background. Here are the main sites I'm using:
https://putlocker9.nl/tv-series
https://putlocker9.nl/movies/library
https://www3.watchfree.ac/search/American+SuperNatural.html
https://www3.watchfree.ac/list/movies.html
https://www3.watchfree.ac/list/tv-series.html
The last three is the site that keeps bombarding me with tabs or windows. Maybe you can check them out and let me know if you have the same problem, or If you can find a circumvention? The adblocker recommended by Mypal is useless there. I downloaded a few addons from Firefox site (like 'Disable Anti-Adblock), but so far, no better.
My custom-build has AMD Phenom x4 9750B (95W), Gigabyte GA-MA770T-UD3P, EVGA E-Geforce 6800 GT 512MB, Asus Xonar D2, three WD Caviar WD1001FALS on mobile racks, one Intel 535 series 180GB SSD, two LG GH24NSC0B burners, and FSP Group Hydro Series 650W power supply, in a Cooler Master CMStorm Trooper SGC-5000-KKN1....the other components are giving me grief to find. No telling how much longer to track down the rest, but fortunately I had the foresight to get this used PC to keep me content til then.