For who's interested: we (not Salesforce.com!) created an improved version of the Excel Addin with the following improvements:

1. Enhanced login-screen: easier switching between environments (less typing)
2. Validation rules are applied by default (by using newer api version)
3. Fixed error on duplicate columns (required custom fields were downloaded twice)
4. Removed default query on 'systemModeDate > [last 7 days]' if no filter criteria were filled in
5. Increased standard batch size from 50 to 200, improving upload performance
6. Removed checks on maximum amount of lines
7. Improved dates handling (sometimes downloaded dates would not upload back into salesforce again)

(update 2012-12-04, 2 more fixes)

8. ability to upload numberic fields as null instead of always 0

9. corrected the bug to cope with error when uploading numbers with many decimals. These were put into scientific notation in Excel but not loaded properly to SF

(update 2013-05-03, 1 fix)

10. ability to query more than 32766 rows (was hitting the VBA limit on Integer size)

Our users are very happy with it. Feel free to try it out or further build on it and let me know what you think:

http://code.google.com/p/improved-excel-addin/

Disclaimer: Though we made and tested all enhancements with great care, we take no responsibility for the consequences of the use of this tool. Also note that this is an open source tool and not maintained nor supported by Salesforce.com.

Regards,

Guy

Hi Guys,

I am using windows7 - 64 bit and office 2010 beta .. just check out the error and suggest what can be done ...

Error is as follows: The code in this project must be updated for use on 64 bit system.Please review and update Declare statements and then mark them with the PtrSafe attribute.

Thanks in Advance