Selection Criteria enabled/disabled based on a checkbox...

Experts,

I have a site (developed in in VWD Express) that uses all the standard stuff (links, gridviews, a little AJAX, etc).  The issue is I would like to be able add a checkbox and a textbox (just above the gridview) where the user could put a check then enter some "Search Criteria" to filter down only specific information.  It would look something like:
+----------------------------------------------------------------------------------------+
| (Header Area)
+----------------------------------------------------------------------------------------+
(Nav Button1) (Nav Button2) (Nav Button3) (etc...)

"Filter this List" ---> [  ]   [ (TextBox1 for Search) ]    (Go...) (do postback)
+----------------------------------------------------------------------------------------+
| <<  <  >  >>
| (GridView)
|  Task Seq#:           Task Applies To:    Task Author:     (etc)
|  -------------------   ----------------------  ------------------  --------------------
|   1                          All                           Bill Smith
|   2                          Managers               Bill Brown
|   3                          Associates             Sue Jones
+----------------------------------------------------------------------------------------+
If the user DOES NOT check the box we continue paging through the records using the "base" T-SQL as in:

SELECT [IDC-Cooper-Project-Activity].[Task-Seq-No] AS column1,
[IDC-Cooper-Project-Activity].[Task-Applies-To] AS column2,
[IDC-Cooper-Project-Activity].[Task-Author] AS column3 (etc...)

If the user DOES check the box (we assume) they will enter Search Criteria...say the word "Bill"

"Filter this List" ---> [X]   [ Bill                            ]    (Go...) (do postback)
+----------------------------------------------------------------------------------------+
| <<  <  >  >>
| (GridView)
|  Task Seq#:           Task Applies To:    Task Author:     (etc)
|  -------------------   ----------------------  ------------------  --------------------
|   1                          All                           Bill Smith
|   2                          Managers               Bill Brown
+----------------------------------------------------------------------------------------+
Using:
SELECT [Task-Seq-No] AS column1, [Task-Applies-To] AS column2, [Task-Author] AS column3 FROM [IDC-Cooper-Project-Activity] WHERE (([Task-Applies-To] LIKE '%' + @textbox1 + '%') OR ([Task-Author] LIKE '%' + @textbox1 + '%'))

(Sorry about the 'visual respresentation' of the screen!)

Is this possible?  Any answers or thoughts would be appreciated!

Thanks,

dmasini