I am just getting into windsurfing and have a 20 year old board which I am managing to sail. I would like to upgrade and buy a mast and sails that I can use with different boards. Sounds easy but I don't know if any sail will go with any mast, or what boom will go with what sail. As cost is a big factor I would like to buy second hand and would appreciate any advice. I am about 80 kg's and will look at a board around 130 litres as my next board.

Most sail makers make their own masts now which suit the sails obviously.
With this you can now buy one mast, and with the right size extension, use multiple sail sizes on the one mast.
For example:
With a 430 X6 Neil Pryde mast I can get a sail range from 5.5m to 7m.
This will allow you much more of a wind range and therefore more time on water.
Any Brand of freeride or x-over sail would be suitable for this and allow you to do a bit of Bump and jump sailing to playing in small waves.
hope this helps a little

this was your first entry into the forum ...
not much information about where you would go and asking a generalized question.
and that after the BIG discussion on what difference carbon % makes in mast response

i always say - beg, borrow or steal something newer ie kidding
take lessons, rent, etc
conditions where you sail?? wind strengths, choppy , currents
do you use a harness, etc etc
i used a long board for 10 years before starting short boarding
and learned new stuff constantly

check: jimbodouglass.blogspot.com/2010/11/updated-windsurf-calculator-online.html
for sizings

also agree about matching sail and mast to manufacturer
at 100 kilos/220 pounds my board was 160 liters and 8.5 sail
this was for light winds
for your weight 130 liter sounds good - i like the Fanatic Shark 135 HRS
this board will go from 0 to pro
my 8.5 is still my most used sail size
so, choose the size for weight, conditions CAREFULLY - maybe 7.0 for you ??
enjoy

Hi Guys,
Many thanks for taking the time to comment on my post. The Neil Pride option sounds good for sails and the Fanatic Shark has a lot of good reviews. Again many thanks
Skulova