Pentium 3-4 CPUS up to SSE2 from the last days of the W98SE era surely are.

I'm currently playing around with a PC I built up from random parts, based on an AMD Duron 1200. I have Windows 98 SE on it. It does feel retro. But then I compare it to my 486, and it suddenly doesn't anymore.

Well, both have the same access to the SSL/TLS web: almost nil. With W95 on the 486 with 32MB of RAM and a de-IE4'ized W98 both would be virtually the same except for the speed.

A Pentium II would be a better example for both: Not too old, not too recent. Yet it suits as retro and a usable machine. Enough to render some XVID videos at 360p and 420p with a good video card. Slackware, NetBSD and lot of distros would still run fine. TLS under Lynx and Gopher would still work, the same as a Gopher client.

I hope to be able to play GL Quake on this Duron PC. The graphics card (ATI Rage 128) should be able to do it I think.

Software Quake@800x600/640x480 under a CRT will look better.

Imo the Xbox 360/PS3 are the newest retro consoles currently.