Beginner T-SQL Question

I'd like to query my Tasks and TaskActivity Tables to return the following results:

Case Id
Estimated Hours
Total Hours
Remaining Hours

Because I'm an SQL novice, I've had to resort to a hack of creating three different views to get the results I want: I'm sure there's a better way (i.e. a single, well-formed query) but when I try that my numbers are all wrong.

Here's my hack to get the correct results:

First I have a view to get my Estimated Hours and CaseId from my TASKS table:
SELECT COALESCE (SUM(EstHrs), 0.00) AS EstHrs, CaseId
FROM dbo.Tasks
GROUP BY CaseId

Then I have a view to get my Total Hours and CaseId from my TASKACTIVITES table:
SELECT Tasks.CaseId, SUM(TaskActivity.Minutes / 60.00) AS TotalHrs
FROM TaskActivity RIGHT OUTER JOIN
Tasks ON TaskActivity.TaskId = Tasks.TaskId
GROUP BY Tasks.CaseId

Finally I have a third view (that I actually use in my program) to put it all together:
SELECT vTaskActual.CaseId, vTaskEstimates.EstHrs, vTaskActual.TotalHrs,
vTaskActual.TotalHrs - vTaskEstimates.EstHrs AS RemHrs
FROM vTaskActual INNER JOIN
vTaskEstimates ON vTaskActual.CaseId = vTaskEstimates.CaseId

Any help would be greatly appreciated, and, if this is not the correct forum for newbie questions like this, please let me know.

TIA,
Rob