I have found a solution! Well, kinda...
I've just tried this so I can confirm it works, but I have Windows 7 so unsure if this will work on Vista too.
Right-click on a column header and select 'Size (All) Column(s) to Fit'. This seems to overrule the 80px limit, at least on columns that have this little data in them.
The only problem is that if you try to resize any other columns after this, it re-enforces the 80px rule again and any smaller columns expand back to 80px.
Could I ask why this is a problem though? Unless you have an extremely low res screen I cant see how saving say 20 extra pixels is going to be benificial.
Anyway, hope that can solve your problem.