Hi Denis,
To start off with, I think that you will find that what you describe may be A [not THE] Goodwin arms. I have a record of 22 Goodwin/Goodwyn entries in Britiah armory.The first one in the list is very similar to the one you describe except that the 'metal' is Or, not Argent. The rest is the same.
The first entry reads:
Goodwin, or Goodwyn (Upper Winchingdon, co.Bucks) Per Pale Or and Gules a Lion ramp. betw. three Fleurs-de-lis counterchanged.
In most circumstances, this would be the one that Bucket-Shop enterprises would sell-off as THE Goodwin Arms. Steer well clear of them as all they do is perpetuate the distasteful pastime of bogus heraldry.
Crest - A demi-Lion ramp. Argent gorged with an Heraldic Coronet Gules.
Motto: De bon volore.
If you want info on the other 21 entries, just let me know and I'll send you a scan of them.
Rgds,