Replacing Characters In A Text Field

I have a large table, tblMessage, which stores e-mail messages in text
fields. I need to remove the carriage returns the data in these fields,
but I have not yet figured out how to do so.

I thought that the way to do this would be with the REPLACE function;
unfortunately, of course, the REPLACE function cannot work with TEXT
fields. I tried CASTing the text field to VARCHAR(8000); however, some
of the rows have more than 8000 characters in the text field, so it bombs.

Here is the SQL that I tried:

select
msgID,
msgSent,
msgFromType,
msgFromID,
msgSubject,
REPLACE (CAST(msgMessage AS varchar(8000)), CHAR(13), '<BR>') AS
newMessage,
msgOriginal,
attID
into tblMessageNew
from tblMessage

I'm at my wit's end. Truncating the text field to 8000 character is an
acceptable option, but I can't even seem to be able to do that.

I'm using SQL Server version 7.