Average life span of a computer

So I've had this comp for about 4 years now and its almost hitting the 5 year mark. I've noticed its starting to slow down on newer games and I have to lower all the graphics to make some games playable.

SO my question is when is a good time to replace my computer? Is getting a new graphics card better or will a whole new computer last longer?

I'd say you would be better off getting a whole new computer.  Things have come a long ways since then.  If you build your own, there may be some parts you can reuse, however.  If you have a sata harddrive, you can reuse that.  You can probably reuse your DVD drive.  You could potentially reuse your PSU if it has enough wattage.

I was just recently in the same position (4 year old computer). I basically bought an entirely new computer, everything but the case and DVD drive. I suggest you do the same.

4 years old, its probly has an agp video slot? Get a new one if thats the case, agp is basically done for and i'd get a new everything.  I had to get a new computer last year to run tf2 (mine was 4 years old at the time), and at about 4-5 years i'd say its time for an upgrade.

Ever sine I bought my computer I've replaced everything and I mean everything but the case, dvd drive, and hard drive. I've also got a floppy drive but who uses those anymore? When I upgraded it was more or less small improvements on what I wanted at the time so I don't blow a huge hole in my wallet...upgrades like this will cost you but you can get some really nice parts (Not nessicarily new top of the line) for some amazing prices these days.

For a gaming PC 2-3 years max with an upgrade mid-way through that cycle, but if you're just doing internet browsing and Microsoft Word then about 5 years.

@OP: you're better off getting a new computer. Even just $500 will do.

they say 2 years for a graphics card and 3 years for the rest of the parts in a gaming computer

I had not seriously considered about this question, but I guess this depends on the computer itself.

My computer is about 4-5 years old and has AGP slots.  It will run all the games I play on high settings at good enough fps.  I have thought about getting a new one as I am sure my graphics card is outdated.  But if it still works then I don't see any reason to get a new setup.