not that I'm a wallpaper expert...but the images seem to have a bit of noise in them.
imo, the better looking wallpapers aren't just a screenshot...usually made of a character (at least one...but sometimes none), the series logo, some nice background, a phrase (sometimes) and a few well placed lines/circles/shapes in general
a wallpaper site
. Doesn't appear to have wallpapers from the ultimate ova 2...but it's Hellsing nontheless
the other thing is the size... wallpapers usually are made at resolutions of 800x600 and 1280x1024 (these are both fullscreen resolutions, and PARs 4:3 and 5:4 respectively)
widecsreen has PARs of 15:9 16:9 and 10:16...and typical resolutions are 1280x768, 1280x720 and 1280x768 respectively (1440x900 is becoming more common)
good job on keeping the image unstretched/squashed