Just because you can't find a use for all that AMD and Intel giveth doesn't mean the world needs to wait for your old box to finally fail to boot before we can come up with ever more process intensive things to do. 3840x2160 4K video is here and 7680x4320 8K is on its way.
I've got a 1.8Ghz Thoroughbred AthlonXP myself, and it was great for quite some time, but you know what it's good for these days? A glorified typewriter w/ built in MP3 player. It can jest barely handle Youtube videos if they are downloaded in no higher then 640x480 in h.264 or VP8, at the very least my old Clawhammer Athlon64 3500+ is able to handle those in 1280x720 on CPU only decoding which no matter how you cut it looks far better.
My Brazos E-450 netbook however can handle 1920x1080 in either h.264 or VP8.
Gaming is almost always GPU limited, the only time it's not is in high number of units RTS games and simulators that are doing allot of physics calculations to have as close to real world conditions a computer can give you.