What's the best way to clean this up?

[Grenou]

You can, but it won't look brand new.
I hope you have a bigger version of this, it makes life easier. (more pixels are better)

In PSP, Promote the Background layer of the image.
Select All (Ctrl + A)
Selections>Modify>Select Color Range
Tolerance 50
Softness 90
Subtract color range ticked.

First use the default colour, ie white.
Click OK.
Then Selections>Invert (Ctrl+Shift+I)
Hit Delete.
Select None (Ctrl+D)

That gets rid of the grubby white background.

Do the above again and sample the brown, using the medium brown to start with is best (don't start with the dark brown or some of the black disappears.
The result is now a bit light.
Duplicate the Layer in the Layers Palette, a few times might be necessary, I did 4. This brings back a bit of the browns, so do the above again.
New Raster Layer>fill with white>drag the layer below the text layer. Merge All.



Grenou