sometimes software programs require a long period of time to shut down, and your machine wont fully go into shut down, until all parts of that program have fully stopped.

it will NOT hurt your machine to hold down the power button for up to 30 seconds (got that from the Dell website)

It may help for you to get something like Ccleaner.com and run the free cleaner that helps get rid of extra stuff that gets left on your machine from installs, and removals, and shifting programs from here to there.

Another consideration is that since the release of internet exp 8 and up to Windows 7 more and more programs are memory intensive. This means they require longer periods to boot up, and more energy to run, and longer periods to shut down. Sometimes upgrading your RAM or random access memory can make those things go faster. Your new hardware that you installed may be a memory hog, and may be requiring longer periods of time to reach a safe point for the machine to shut off.

go thru your normal shut down routine. Keep a timer on how long it took for your machine to completely shut down without you having to interviene with the mashing of the power button, or unplugging it. It can take up to 15 mins if something is pulling loads of memory away from the machine for its own purpose. If it take an extra long time, disconnect from the new hardware you installed, and re time how long it took to shut down. If it zipped thru, then you know you need more RAM on your machine in order to shut down faster, OR you need patience for it to go thru its cycle.

Either way, the Ccleaner.com program is a nice one to clean off the extra stuff that we all collect and bogs us down. One of the tools on it is "start up" and it will explain and let you chose which items YOU want to start when the machine starts. Like adobe updates. I dont want that bogging me down when I start a machine or those pesky java updates and so forth. I want adobe to only start when I click on it, not before then. it lets you pick your programs.

Till then, you are not hurting your machine to mash the shut down button.