I do not think so, at least not easily. HOWEVER:
My XP-SP3 refused to install for months, but automatically
detected that and rolled itself back out.
Something changed, it liked the change, and then it
"fell in", just like it was supposed to...

There is more info here, and MS should help you (free).
<http://support.microsoft.com/?kbid=936929>

Rick Glazier

From: "Robert Citkowitz" 
> Does a failed or problemmatic SP3 installation allow reversion to SP2?

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