If you have a big monitor just unlock the taskbar and drag the
edge of the taskbar up and double its size. If you auto-hide the taskbar it doesn't really matter if it's bigger. This way XP's clock
shows the date, time and day of the week. It saves running
another program and wasting resources.
I had used it with W-95 and really liked it.
I notice that it wasn't listed for XP but I know of other people using it with XP, so I just downloaded and installed.
I don't know what you mean by compatibility mode?