I would pass on it if you plan on trying to use VLC - IIRC the og's only support 480p content reliably. I might hold out until you can find a cheap 2006-2007 Intel Mini.
For 1280x720 (720p) video at 24-30 frames per second:
QuickTime 7 for Mac OS X: 1.8 GHz PowerMac G5 or faster Macintosh computer; 1.83 GHz Intel Core Duo or faster
At least 256MB of RAM
64 MB or greater video card
Hi everyone (first post after active lurking); I bought that same OG Mini some six months ago and despite being fun to mess around in Tiger/Leopard hardware limitations are pretty severe and disc drive has worn out. Boxing it for now but in no way do I regret the purchase. A nice piece of history and (one of the) last PPC machines.
I bought one of these back in the day, but even back then, brand new as it was, I thought it was a slow and limited computer.
It has some merit as a compact retro software machine, as it will run both Classic OS 9 applications, and OS X PPC applications. But I don't see how it is viable for any modern use--maybe you could use it as a slow file server or something.
Probably the oldest Mini I would consider is the 2006 Core Duo. At least it has two cores, gigabit Ethernet, and the Intel processor can also run Windows or Linux. Plop in an SSD and it might even feel peppy.