SQL 2005 Update Query

OK you T SQL query experts try this one out;
I  have two tables;
1. "Vendors", containing 200 unique Vendors names [ varchar(30)] and matching Expense Codes [int(2)], 2. "Transactions", containing 20,000 transaction Descriptions [varchar(200)] , ExpenseCodes [int(2)] and $ Values.
A one-to-many relationship exists between Vendors and Transactions and a vendor's name may be located anywhere in the Description field of the "Transactions" table.
I want to update the ExpenseCode field in "Transactions" from the Expense Code data recorded in "Vendors" based on a match of the vendor's name anywhere in the Description feild of the "Transactions" table.
Full Text Indexing is enabled on the Transactions table.