@Skimask
Even with all of this noise problems I'm having, I had no problems working with logic level signals at all. This scope won't catch very fast glitches, but if you need to take a look at general purpose I2C, SPI,RS-232,RS485, low or full speed USB and other slow protocols, then it's OK. Of course, it doesn't have protocol decoding, so you'll have to work out by hand what's going on and there's no memory segmentation either.
UPDATE:I made a bar again and this time used 1 µF capacitors between all lines and the bar. Now I have results which are relatively close to the good ones I posted few pages back, but only when the probe is in the fixed position as shown few pages back. If I move it away, then I get the new spikes back, but they aren't as bad as before. This was made when running on battery. I'm a bit concerned how the AC trigger signal is going to work with such a big capacitor on it, so I'll probably go back and change that one capacitor to something lower.