And since on a modern graphics card you're lucky to get one analogue output, let alone two, I am also finally replacing the ageing CRTs with a pair of LCDs (pleaseremove was almost speechless when I mentioned this to him). I'm probably going to get a pair of Dell P2214H displays, chosen because they're IPS-based (one reason I did stay with CRTs is colour quality on LCDs is still often an issue), and because they have DisplayPort (the graphics card mainly has DisplayPort outputs).
That's about it for Nyx - to upgrade it any further would require a motherboard replacement, and to be honest a Core 2 Quad Q6600 is still a reasonable processor. However that's not the only system I've got... yes, Aether is also being upgraded (pleaseremove's reaction to this news was equally hilarious - while Nyx is getting a cutting edge GPU, for Aether it's whatever I can scrounge on eBay). eBay has a few Pentium M processors for around the £20 mark, so I'll probably fit a Pentium M 755 for a nice 33% increase in CPU performance. While I'm at it I also intend to upgrade the heatsink - yes, this is actually possible! The reason behind this is the current heatsink/fan only covers the processor, while the GPU just has a little passive heatsink attached. This is not really ideal given that unlike the R50e there's a real GPU in here (ATi Mobility FireGL T2), and as a result that runs a good 20°C hotter than the CPU. Now it turns out that the R50-series and T40-series ThinkPads share a lot of structure, except the T43p has a combined CPU/GPU heatsink and fan. And it's apparently possible to fit the latter to a R50p with a minor bit of modding (trimming some plastic). For another £20 I think this is worth a try and should help it run a bit cooler.
Finally, Aether is also going to be upgraded to Windows 7. Probably Professional - Home Premium would likely be sufficient, but I'd end up missing the extra features from Pro. I've found drivers for everything, even the GPU (or rather Windows Update contains drivers for everything which is enough to get started with), so that's not an issue, and XP is getting increasingly problematic as more and more software these days assumes Windows 7 as a baseline. Firefox is an example here - some digging suggests that it does actually support video hardware acceleration in the form of DXVA2, but only on Windows Vista or later. So despite the higher system requirements the laptop should perform better.
Windows 10 is probably a bad idea though.
Long-term I'm waiting to see what happens with the new retro ThinkPad that Lenovo are considering. The currently crop of ThinkPads aren't actually that nice to use - $WORK has issued me a T440p with the worst touchpad ever (and the Trackpoint is hardly better because they removed the buttons for it) - but it looks like they're seriously considering releasing an actual ThinkPad. If and when that does happen then I may well upgrade to it, but given that it's probably a year away I think it makes sense to keep the R50p going.