A normal message window size to plan for would be 800 pixels or fewer. A graphic in a sig should stay under 200 pixels (in my opinion) or smaller. Large graphics can be a turnoff for some users. 72 DPI is fine, as the graphic is not intended for high detail viewing. Just my two cents...

Thanks for your reply. I tried to resize the graphic as you said, 200 pixels wide, 72 dpi, it came out an very blurry image.

Okay, but 72 or 96 is common. If you would like assistance, email the full graphic to me at davidthunderbird at gmx dot com and I'll see what I can do.