Well obviously you're definately new to midi-audio recording through pc/mac.
Seeing your target to do some strings only in the studio in a couple of month's and your pc is a laptop you are probably best of with hardware.
If going the software route you need knowledge of; midi - sampling - sequencers - audiorecording software - soundcards etc..
Within your budget I would look for used gear though.
My guesses are that by layering the strings
you mean multi-track audio recording in the studio? (track by track recorded.)
you could look for;
Yamaha DX 7 (saw these around euro 300 used)
Roland JP8000 (around 700 euro used)
Another nice one could be a Roland MT32 but that one is without keys, so you need a keyboard controller as well which rules it out as you need some midi knowledge.
I am sure a lot of the members here have a lot of other suggestions but I try to think within your budget for easy to find used synths models
There is a site on harmony central with reviews of most synths so it is worthwhile looking to get an idea.
http://www.harmony-central.com/Synth/Data/ Let us know if you need some more info.
Fred
[This message has been edited by freddynl (edited 10-21-2003).]