After creating a 2.5gb Primary NTFS Partition in XP with #8 (IM-magic resizer) on the following list, b/c programs that said they support XP actually don't (I tried #1 minitool, #3 easeus, and #6 macrorit):. https://www.softwaretestinghelp.com/win ... n-manager/
Small side note:. For some unknown reason Gparted started working without me doing anything to get it to work after it giving me a message before that it needed something downloaded. So I could have used Gparted to create the partition, but due to Mikeslr's recommendation not to (on another thread) I used IM-magic Resizer.
I then moved on to install Tahr. Used Gparted to reformat the designated partition to ext2, because IM-magic only has the options of NTFS, FAT16, or FAT32. The only other thing I had a choice about (where I could've picked the wrong thing) was where I wanted to install it, which I told the installer my computer had a IDE/SATA hard drive rather than SCSI.
After the install, Tahrpup has 1.43gb free space to work with in its partition. It seems to look the same as when Tahr runs off the DVD, including Newmoon's behavior (adds to the menu, but won't display). The only major difference I can see in the Full installation vs. booting via DVD is that Opera (along with several other browsers readily available in quickpet) would download+install when running off the DVD, where it (they) won't even download in the full install. This makes me wonder if this glitch in Opera is also affecting Newmoon (tho I doubt it since Newmoon should just be running off the USB, but I also moved it onto the partition's mnt/home), but with me not knowing how to fix it, it probably doesn't matter...the fact is the full install doesn't work as I had hoped - actually worse than the original set up I tried.
So with my little IBM thinkpad T20 appearing to hit the RAM wall limit, looks like I'm down to needing to make a decision:
A) use the computer offline only
Or
B) If I want to access limited Internet via Opera 12.15 on Tahr - run it from the DVD w/ a savefile in place (which I'd probably hand back XP the 2.5gb I took from it)...unless some1 has a way to fix it on the full install??
Or
C) buy more RAM to max it out at the 512mb level to attempt to get Newmoon working on the full install
If any1 has any ideas where to buy cheap RAM, I'll take it b/c I'm not seeing any anywhere ( I'm seeing ~$50). If I could get RAM as cheap as Mikewalsh did at 6gbp, I'd be willing to invest that much into this idk-how-much used machine that is estimated to have a max. Life span of 5-7 yrs, despite being warned not to invest any $ into a computer that's 10+ yrs old.
Otherwise, it appears I've tried everything I can. Unless any1 has any last Hail Mary ideas, I guess I'll consider this matter closed + no longer ask any questions about it, resigning myself to the fact that I have 3 primarily, if not fully, offline-use-only computers.
Thank you all for all the feedback. It's been an interesting journey. 