help importing external excel file

I am fairly new to SQL - can anyone give me advice on how to import new data
only from an external excel file. The data for the excel file will change
approximately a few times per week.

I have been trying to schedule a DTS import but will this check for existing
data - I do not want to import duplicate rows, can I run this someother
way - instead of scheduling to run every day can I have it run only when
changes are made to the file?

I would appreciate any advice on how to accomplish this.

Thanks

joann