that's because you converted the 256 colour gif to png, instead of the 23812 colour source picture, even with maximum compression using irfanview, I can't get the filesize below 130 KB
bottomline:
-gifs have only 256 colours, which is not really a problem unless the source contains a huge amount of unique colours
-png has superior compression techniques compared to gif and supports 16.7 million colours, but if you have a large amount of unique colours in your picture, filesize
can get large, also, transparently does not work correctly in IE (which a huge amount of internet users use, and I don't think they care about IE not being a browser, I know I don't
)
-jpg also supports 16.7 million colours, and has great compression (really useful if some mod orders you to get your sig size below 30 KB
j/k ), but has no transparency and compression is loss
y
I'll quit here, it's not like we're ever going to agree 100% anyway