If your Windows 7 Excel 2010 does not give you the option to put brackets on negative numbers or currency, here is the fix that worked for me.
1) Click Start -> Control Panel
2) Click Region & Language
3) Region & Language window, Click Additional Settings
4) Put () in the Negative sign symbol, click the Currency tab and choose ($1.1) selection under the Negative currency format
5) Open excel worksheet, select cells to format and right click then format
6) Under the Custom, select the option with the brackets