How do i make a column using 3 other columns together within the same table

The example to this question is better:

ID PName Ppurchased PSold PSellPrice AvgSellprice
1 Water 50 10 100 20
2 Water 40 20 200 100
3 Water 70 35 50 25

What i want to happen within the table or maybe on a different table is to add the AvgSellprice of all 3 together to where it will look like this in a table:

ID PName Ppurchased PSold PSellPrice AvgSellprice TotalSellPrice
1 Water 50 10 100 20 145
2 Water 40 20 200 100 145
3 Water 70 35 50 25 145

Or maybe a new table which i want to look like this:

ID PName TotalSellPrice
1 Water 145

I know i can get the TotalSellPrice from the query:
SELECT SUM(AvgSellprice) AS TotalSellPrice
FROM tablename
WHERE PName='Water'

Also i am using MSSQL 2005 if this may differ. Thanks for any help.

[812 byte] By [Rezzel1234] at [2008-2-10]