pl => poland; perl
xv => 15 (in roman numerals); xview (old GUI); subliminal phonetic almost echoes "sexy"
lx => lex; luxury
plx => plex
all in all a bit of a stretch but not totally "unbrandable" IMO
I'd be more hopeful about demand in near term if any sign of life in other ccTlds such as plxv.pl / plxv.cn / plxv.com.cn
as is, undeveloped:
right now - reg fee up to maybe $10
January 2008 - $30 to $60
January 2009 - maybe $100
just guessing, I don't really know - seems worth holding for a while to find out what the scarcity premium will be.
Personally, I like PLXV.com - not bad for line noise - almost pronounceable even. Good luck with it !