Paging is a popular topic with no easy answer. I've seen a couple of techniques, most make use of server-side cursors to allow for jumping to absolute positions.

I have one idea but I've never had an opportunity to implement it. If you know the column that you want to sort on, the value and PK from the first row and the value and PK from the last row, it becomes easy to page throught the table.

To move to the next page:

SELECT TOP 50 *
FROM table
WHERE column >= last_column_value AND PK > last_PK_value
ORDER BY column, PK ASC

To move to the previous page

SELECT TOP 50 *
FROM table
WHERE column <= last_column_value AND PK < last_PK_value
ORDER BY column, PK DESC

This last set will return the value backwards. It shouldn't be too hard to flip them.

-Mike