Ok people, i've been doing some sniffing around on the net for an affordable GPS and i've come down to these two... Garmin 172 or navman 5110. Both are b/w which is fine with me as i cant really justify the extra cost for colour. What im after though is your advice on the performance of these two units as I have had next to no experience with gps plotters before. US website cascade marine has them both for under US$300 which is a lot cheaper than i could find anywhere around here. Also i would like to know your opinions on the c-map(navman) and bluechart(garmin) navionics cards. Thanks! - simon.