Do your research, then write a report. (Score 1)

Don't tell people "no" -- it's not what they want to hear, and even if they accept it, they're going to be far less than impressed with you.

Rather, if there are tradeoffs involved, then tell your boss what the options are. Often, PHB's don't understand that software development/ IT/ etc isn't like digging a hole: you can always dig a hole faster, given sufficient incentive (a levelled gun, for instance). But computing doesn't work way. There are whole branches of software engineering devoted to just that principle.

For instance: in a five-day period, you may be able to:

• take support calls and only have time to maintain the disk servers and backups, or
• only maintain networking equipment and perform upgrades, or
• etc.

Do your research. Find out what resources are required for x, y and z. How long does an upgrade take? How much time is spent configuring new routers? Tabulate your findings, and present them to management -- and let them work out how to say 'no' to their bosses.

And best of all -- if you do that, you're the good guy who had the initiative to do the research in the first place.