Yes, this old chestnut…I thought I had posted this ages ago, but I don’t see in the archives, so:

If you want to check if an object exists, and you don’t want to deal with any error handling, then do it this way:

from sipyutils import disp		# win32com.client.Dispatch

def objExists( name ):
    c = disp( "XSI.Collection" )
    c.Items = name
    return not( c.Count == 0 )

print 'Object does exist' if objExists( "XSI_Man.geom" ) else 'Does not exist'