Were I a citizen of Ukraine, I would vote for Yuschenko, that's for sure -- like most educated young and young-ish Ukrainians. As I see it from up North, Yusch's problem is that Western Ukraine supports him all too ardently. The West is the most economically backward, the most rabidly chauvinistic and anti-Russian bit of Ukraine that almost managed to hijack the Ukrainian nationalist cause without a slightest right to represent all of the country.
That scares moderate and/or Russophone and/or bilingual Ukrainians. (Not to mention the West is Uniate while most of Ukraine is nominally Orthodox.) If Western Ukraine belonged to Poland now as it did before 1939 and Molotov--Ribbentrop, Yuschenko would have two or three million votes less there but easily five more in the center and East of the country.
Putin apparently supports Yuschenko's opponent, Victor Yanukovich, but I'm sure Moscow is talking secretly to Yusch as well. The Kremlin must be trying to hedge its bets.
Unlike Russia, Ukraine has not gone through its Yeltsin period, with bouts of rapid liberalization and lightening-speed, corruption-driven privatization. There must still be plenty of room still left for future disappointment in the hearts of Ukrainian voters.