One of my laptops is a Dell Latitude 620, its old and has problems.
The live version of Puppy linux is worth a try, it can breathe new life into old pcs.
It may be worth trying before you spend your money on a new pc.
The laptop which I am using to post these replies is about 10 years old, has 256mb of memory, & a 500mhz processor. (built for Windows 98) It runs Openoffice which is compatible with microsoft office.
Its a simple download & burn to cd/dvd so worth trying.
It is a lot faster than most of the current pcs that I build with Windows installed. From pressing the "on" button, to surfing the internet takes about 30-40 seconds.
Its free, & wont affect your current version of windows. so worth trying. :-))