Been a PC gamer since 2001, now let's see...
Intel Pentium III 1.0Ghz, 128MB SDRAM(Upgraded to 256MB around 2003), Nvidia TNT2 with 32MB of VRAM and 40GB of hard drive space, decommissioned at 2004, used to run some light weight sims like Micro Flight quite nicely with a 15" LCD screen -- That thing's expensive back then.
Intel Pentium IV 2.93Ghz, 1GB DDR SDRAM, Nvidia GeForce FX 5200 with 128MB DDR SDRAM and 80GB worth of secondary data storage. Still sitting under my table with a relatively new ATI Radeon 3650 on the AGP slot of the old FX 5200, a standalone sound card, an additional 160GB hard drive, and a shinier heatsink on the processor in a major overhaul back around 2008.
Inter Core 2 T9300 2.50Ghz, 2GB DDR2(4GB after 2009), Nvidia GeForce 8600M and 256MB of GDDR3, 200GB of hard drive space and a free heater in winter, in my current, yet (I know) outdated, XPS laptop. Runs things like Freefalcon and FSX fine with a Saitek stick, and SAM Simulator on a Windows XP VM with the necessary resolution.