Hi P-T
First off, note that OFP will in fact use any old sound type you care to use (AFAIK). I gave up on .ogg files years ago and now just use common old wav's for my custom sound effects.
Second, for sound effects try Sound Dogs, here -
http://www.sounddogs.com/start.aspThey have a virtually unlimited collection of sound clips on any topic you care to type in. Apparently, you have to pay for the full length, high quality clips but I've never paid a cent there - all I do is take the free clips that my searchs turn up.
Note that the clips are in MS's wma format but you can get a free converter from the net, just go to Google and type in "WMA converter". Easy as !
For voices, try this site -
http://www.scansoft.com/speechworks/realspeak/This is a TTS (text to speech) site, you can use their little sample utility to create short voice samples (eg "Alpha 2 6, move to Le Moule."). The samples have no real emotion so you can't create screaming squadmates cries for help etc, but it does standard speech really well and there is a fairly wide selection of accents and dialects that you can use. Highly recomended !
And again - FREE !
Man I love the net !
roni