Seeing what it can do...

 So the final build is:

• Core 2 Quad Q9450
• EVGA 132-CK-NF79
• 8GB 1333MHz DDR3 RAM (dual channel)
• 1GB Radeon HD 5850
• 320GB 7200RPM SATA HDD
• EndeavourOS

...Removed jack2, added Remmina+RDP and Steam, and that's about it.

Steam works much better here than it did with the 8800 GTS, and I really wanted to see what it could do - so I installed some heavier games with native Linux support that would take advantage of the 5850. Started with Bound by Flame, but it wouldn't display anything; tried Painkiller: Hell & Damnation next, and it would crash after the splash screen; then I started troubleshooting and it turns-out both are apparently awful Linux ports that don't really work - so I played it safe and went with Portal, which ran great at 1080p w/max settings. Looking at what I haven't really played in my library, I'm thinking the Penumbra trilogy and Shadow of Mordor are the way to go. Next experiments might be to see what can be done with Proton on a GPU that doesn't support Vulkan, and how well Electron-based GeForce Now implementations work here; but the takeaway from all of this is that the C2D+3870 and C2Q+5850 make for solid Linux desktop computers with decent gaming options. Not sure I'd throw any real content creation tasks at them, but pretty happy with the results for spare parts and a free, modern OS.

For fun, I installed both the original Black Edition and the Hell & Damnation remake of Painkiller on Windows and... What the hell? The remake is awful! Why were reviewers so forgiving of that unnecessary trash, especially when the original holds-up so well!? Anyway...

Forza Horizon 4 Ultimate Edition and Mortal Kombat 11 Ultimate were both on really good sales, so I splurged. Forza's nice, but the Ultimate Edition bonuses immediately gave me enough "influence" to just skip three of the four introductory seasons... Kinda wish I'd gotten to play more of those. Otherwise, this was the fastest I've earned an F40 in any game, my upgraded orange-on-white '73 Carrera RS is probably the closest I'll ever get to driving a Singer, and call me cliché but I love my Sport Quattro S1. Haven't touched Fortune Island or the LEGO stuff yet. As good as this all is, however, I think I'm ready for a new Need for Speed game.

MK11 is boring; I think the series peaked in 2011.

Traded-in a bunch of old/random/scratched/free PS2, PS3, Wii, and Vita games for Metroid: Samus Returns, Xenoblade Chronicles X, and a Wii MotionPlus... Though to be fair, one of the trade-ins was a sealed copy of Demon's Souls for PS3 that I got for free years ago and never opened :)