olrac,
looking at the EXIF info from the first pic you posted, you shot this with your lens set to 220mm @ 1/50th of a sec. (I'm assuming handheld as well ??).
The light levels when you took this shot (6.05pm) would have been very low and even in good light, 1/50 sec. is way too slow a shutter speed to be using. This will be the reason for a soft and blurry photo.
With your 70-300, you need to make sure that the shutter speed (at least) matches your focal length,
if not compensate a little more for good measure (to factor in the x1.5 crop factor).
At 220mm, you really wouldn't want to shoot under 1/200th sec. preferably 1/300th (or more) if you have enough light.
You will soon realise that this is virtually impossible with this lens at those light levels. To try and combat this, you can:
a) bump up the ISO - which probably won't help enough
b) use a tripod, slow shutter speed to expose correctly and perhaps even self timer or remote shutter
c) save your pennies for that 70-200
f2.8 VR lens
d) try using flash if the subject is close enough
e) keep taking grossly underexposed photos...
Depending on the subject/scene, I usually try D and/or B 1st, then A. (I'm not allowed to try C
)
When you shoot, you should always note in the viewfinder what the exposure meter is telling you. If it's a little off centre, a fine adjustment will help you, but if it's way over to the left or right, the shot ain't gonna come out good (under most situations).
Learn to read this and it will save you lots of heartache when you upload your prized shots to see darkened images....
Hope this helps