If conversion and recalculation isn't what you're looking for, normally Excel picks up regional settings from the system. It should be your default, I would think, if you're in Europe. Regardless, search HELP for Euro or currency. I see this in the off-line HELP for my Excel2003:
Format values in euro currency style
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This process does not convert cell values.
Select the cells that you want to format as euro currency style.
Click Euro on the Formatting toolbar. If Euro is not available, you must load the Euro Currency Tools add-in program.
On the Tools menu, click Add-Ins.
If the add-in you want to use is not listed in the Add-Ins available box, click Browse, and then locate the add-in.
In the Add-Ins available box, select the check box next to the add-in you want to load, and then click OK.
If necessary, follow the instructions in the setup program.
Note The regional settings for currency in Microsoft Windows Control Panel determine the position of the euro sign (that is, whether the symbol appears before or after the number and whether a space separates the symbol and the number). To change this positioning, create a Custom currency style. The regional settings for currency in Control Panel also determine the decimal symbol and the thousands separator.