SharePoint - create an issue tracking list

I am trying to create an issue tracking list which takes a number of input criteria to determine the criticality of the reported issue.

Sites to refer to: http://www.nothingbutsharepoint.com/ and http://blog.pathtosharepoint.com/

The general criteria are:

1. Time Tolerance - how long can user tolerate the issue/ downtime
2. Functional Impact - which aspect of the business is impacted
3. No. of Affected Users - how many users are affected
4. Availability of Alternatives/ Workarounds
5. User Type/ Category - who/ which group of users are affected

Based on the above input, some scoring is assigned and criticality is finally determined.

I created the following Choice columns in the list with the fields preceded with a (x) to number the choices.

• Tolerance:  (x2)
  1. half day (5),
  2. 1 day (3),
  3. more than 1 day (1)
• Impact:  (x5)
  1. Others (0),
  2. Sales (5),
  3. Financial (5),
  4. Reputation (8),
  5. SSO/ Email/ Network (8)
• Affects:  (x5)
  1. Individual (1),
  2. Business Unit (3),
  3. Department (5),
  4. Site (8),
  5. Enterprise (13)
• Workard:  (x2)
  1. Yes (1),
  2. No (3)
• User:  (x3)
  1. CEO (21),
  2. VPs (13),
  3. Customer (8),
  4. Agent (5),
  5. Staff (3),
  6. Govt (2),
  7. Partners (1)

The Scores are then mapped to the following table:

• 90 - Critical
• 80 - High
• 50 - Medium
• 1 - Low
• 0 - None

An additional column is created to calculate the score based on this formula:

choose(right(left([Tolerance],2),1),5,3,1)*2+
choose(right(left([Impact],2),1),0,5,5,8,8)*5+
choose(right(left([Affects],2),1),1,3,5,8,13)*5+
if([Workard] = "Yes",1,3)*2+
choose(right(left([User],2),1),21,13,8,5,3,2,1)*3

A final column is created to display the criticality value:

if([score] > 90,"Critical",
if([score] > 80,"High",
if([score] > 50,"Medium",
if([score] > 1,"Low","None"))))