However, I went from 32 to 64 bit. 2GB ram to 4 GB ram and 500GB HDD to 1 TB HDD.
This PC is now like greased lightning. It only took me a day to get EVERYTHING I wanted loaded and customised the way I want it. Each program loaded quickly but it always takes time to set things up the way you like them.
My last computer lasted me 7 years so that was pretty good. But it had some hardware and software issues so this new one has no issues at all.
So if you do have problems, upgrading is a great way to solve problems if they're too many to keep you happy. My old pc was also very slow and seemed to be getting slower.