To put it bluntly, the US and Russia haven't gotten along lately. Which is extremely unfortunate considering Russia's huge stockpile of WMDs and its abundance of natural resources. These two factors alone, potentially make Russia more of a threat to the US than anything brooding in the Mid East.
US policy has been completely reckless in terms of its approach to Russia, and is the primary cause for the recent relations. The US has: increased its military encirclement of Russia with new NATO and US bases in former Soviet countries (this after Bush I promised the Soviets in '90 to not expand NATO "one inch to the east"), US denials that Russia has any legitimate national interests outside of its own territory (even though most of the former Soviet countries populations are ethnically, linguistically, maritally, religiously, and ecnomically linked), treating Russia as if it doesn't have sovereignty within its own borders, and the US's recent attempts to achieve nuclear superiority (withdrawl from ABM Treaty in 2002).
These policies have caused Russia to cooperate less in many different areas, and they are now more sensitive to issues that concern their sovereignty. Moscow has begun to intrepret the "color revolutions" as clearing the way for NATO bases. Effectively turning them away from the West, and into the arms of the Shanghai Cooperation Organization (also known as NAMBLA). The revolutions also make Russia further embrace the local despot in Belarus, and crack down on democracy within the Motherland. Also, the US would have more leverage in critizing Russia's crackdown on democracy--and supporting other nefarious acts at home and abroad--if the US didn't buy oil from despotic regimes in Kazakhstan and Azerbaijan.
It is important to note that Russia could make life a lot more difficult for the US, but it hasn't despite all the actions taken by the US. If it wanted to, Russia could: easily penetrate any "missile shield", give more aid to seperatists movements in Georgia, shut out US businesses from lucrative contracts, redirect its natural resources away from the West, and use its power on the UN Security Council to veto any proposal.
What the US should do is stop the expansion of NATO--it is an anachronistic organization anyway. If Ukraine is absorbed, things may come to a breaking point (it may also be undemocratic since a majority of Ukrainians are opposed). The harsh rhetoric, particular by VP Cheney in recent months, must also cease, and a return to the ABM Treaty is imperative. Lastly, interfering in Russia's internal affairs only harm chances for political liberties and give hard-line Russian politicians higher approval ratings.