How often do you get new hardware to update your computer?

It happens whenever I feel the need for it. Last time I upgraded my current computer was almost exactly 2 years ago when I gave it a new PSU and a new graphic card, and guess I won't do any further changes until 2015 or maybe even 2016. Well, unless something breaks down I guess

Aside from adding a hard drive, and removing one other, not since prior to 11-11-11. Most likely won't do anything more with it until FO4 comes out, in which case I'll probably build a new one. Might reuse a few of my parts for this one though, it'll save me some cash if I do.

For some reason, I feel like a poll should be a part of this topic.

But to answer your question ... overall, not that often, assuming nothing actually breaks. Sometimes I'll decide I want more or faster RAM, if it's available, now and then I get another HDD (or external usb HDD) (edit-more for backup space vs. "upgrade"). But sometimes, I don't need/do any of that at all...depends how thorough I was when I built the PC in the first place.

Outside of that, I'm likely to get a new video card once or maybe twice during the lifetime of the PC ... the lifetime usually being about 6 years for a "main" rig, before I feel like I want to/have to build an entirely new one.

Very rarely. Even though my PC is over 10 years old it's not old. I know that makes no sense, lol.

The motherboard had to be replaced when it was still under warranty, so that and the cpu are probably a little newer. The case itself is the oldest. I've only replaced the case fan, added more RAM and bought two video cards in its lifetime. The card upgrades were due to games, otherwise nothing wrong with the original. The DVD drive started dying so that was replaced, as well as the PSU, but they were taken from another PC in the house. There was nothing wrong with the PSU but the video card I bought for Skyrim needed something better than 300W.

I'm still using its original keyboard, but have gone through dozens of mice and several speakers, though only changed the monitor once.

My PC is still fast enough to meet the recommended requirements for most games, except the latest Metro that has an operating system requirement

It's still fast at 3.2ghz, a single core (with hyper-threading, so technically a dual core, anyway, or so I read).

If I upgraded it again it'd only be the video card, possibly the PSU, but due to my case size the 550W Corsair I have in its box in the corner won't fit, so if I need something bigger than what I have at the moment (430W) I'll just buy a whole new PC. No big deal, I'm saving up for one, anyway

Never, unless is breaks beyond repair - which is also never happened.