Strategic IT -- IT assest/project management

[Like any asset IT is a resource to be managed.  The resource has a cost and must deliver an adequate return/ROI.  Projects must also be delivered on time and within reasonable budgets variances.  Please develop a guideline that ensures:

(1) IT spending and investment will be alighned with corporate objectives
(2) The risk of bad IT implementation outcomes are mitigated]

Ideas/suggestions:  Please discuss in general the appropriate metrics that one may need to track.  Also discuss how investing in IT with an eyes towards the replacement/automation of another project/issue or task may work (e.g., if Company Z invests in technolgies, A-C it may be able to shut down more antiquated systems and realize the higest ROI amongst the existing projects in the portfolio.  

Treat and analyze the list of IT projects as a portfolio whereby different ROIs and payback periods may differ for projects based on a segmentation of:  (1) Strategic Importance (e.g., High - Low) by (2) Ability to Execute

or Strategic Importance today (High-Low) vs. Strategic Importance Tomorrow (High-Low).  This framework can describe IT projects that fall into the following categories:

Legacy (Low - Today, Low - Tomorrow)
Falling Stars  (High - Today, Low - Tomorrow)
Stars  (high - Today, High - Tomorrow)
Rising Stars  (Low - Today, High - Tomorrow)

Tomorrow represents the near/long term.

Thanks!