New boy at this. (prob with misnamed files)

[Unclebill]

Hi all,
first the system information,
XP Home + SP2.
Intel 6700 @ 2.66Ghz
2GB Ram
500GB disk
Limewire 4.14.3 JAVA 1.6.0_02
Cable modem (no idea of serial numbers etc.)
ISP was NTL now Virgin.
ZoneAlarm and Adaware.
Working from home.

I've used Lime Wire now for about a month with no problems, download speeds fluctuate quite a bit but not too disturbing.
One niggle --- how do you know that what the file name says is actually what you will get??

Twice now have downloaded files named one thing only to find that they were something similar but not as advertised!!

I understand how to use the preview button but sometimes the download speed can be very slow and a lot of time is wasted before you realise that the download is not what you want. Is there any way of verifying what the download actually is before starting the process??
I hope that I have gone about posting properly, I'm not very computer literate so is the 'New Thread' button the right one to have used?

Anyway, glad to be here and look forward to fruitful communications.