Help with first Excel Data Import to SQL

I am running SQL 2008 and have a spreadsheet I want to import into the table dbo.prod_vendor_purch_default

The table has 3 columns:
prod_vendor_purch_default_guid (primary key)
prod_guid
vendor_guid

I have the prod_guid and vendor_guid listed in the columns in my excel spreadsheet.

I need to insert these values into the table while creating a new guid for the prod_vendor_purch_default column for each row.

I tried using a column in excel that has lower(newid()), but it does not seem to be properly recognized during the import (I get a duplicate record entry-not allowed). So it appears to be attempting to insert the text 'lower(newid())' instead of actually generating a new id.

Unfortunately I cannot use the bulk import command (I am accessing a remote database and do not have that permission).

I am connecting to the database using SQL Server Management Studio.

Any guidance would be much appreciated.