From its appearance, it's probably from the early 1990s - I've got a Toshiba one that looks very similar (may even be the same OEM system) from around that time somewhere in the store-room.
If it's from roughly the same time, and was mid-market rather than top-of-the-range, it's most likely a 486 at 25-33MHz, probably with 4MB RAM. Hard disk - probably around 80-120MB. The screen is most likely a monochrome STN, 640x480. Colour ones did exist but were a) horrendously expensive and b) almost unusable because the LCD response time was so slow. (I remember using a laptop with a colour DSTN screen in around 1999-2000 and the windows used to "fade in" when you opened a program, not because of some kind of visual effects but because the panel had a 450ms response time! Watching a movie on VideoCD was impossible.)
You could run Windows 3.1 and set up some old-school programs like WordStar for Windows (I spent many hours using it for homework and remain to be convinced that the latest version of Office really does anything extra that I need which I couldn't do just as easily on WSWin) to get the nostalgia going
(I've still got the installation disks for all that old software somewhere - I ought to see if they're still readable and archive them for posterity!)