This poll is interesting in that it confirms the Forum Research numbers of last week, yet at the same time, as Harris-Decima does, overestimates the Greens (changes from the last poll in brackets):
Harris-Decima (Federal - April 30th, 2012)
New Democrats: 33% (+1) - 119 seats* (-3 seats)
Conservatives: 30% (-40) - 117 seats* (-24 seats)
You'll notice that the three main parties have their seat counts with a little asterisk - this is because, for some odd reason, Harris-Decima only gave the regionals for Ontario and Quebec. I was forced to guesstimate what other provinces were at - luckily the changes in the two main provinces accounted for a lot of the national movement anyways.
This is because the biggest change was in Ontario, where the Conservatives dropped from 41% to 33%, and the NDP rose from 24% to 31%, and the Liberals inched up their own point (but thanks to the Con drop, earned quite a few seats). That accounted for a roughly 2.5% drop in the Conservative national vote.
Quebec also explains why the NDP, despite going up a point nationally, actually lost seats. The Bloc jumped from 24% to 29%, a very good number for them, while the NDP remained steady at 39%. Quebec is increasingly becoming a Dipper-Bloc fight, though the separatist party is failing to make major gains as of yet, just keeping themselves steady - a feat in and of itself, giving their poor fundraising as of late.
When (or if) Harris-Decima gets the full regionals out, I'll update the above.