Background noise removal

Hi Folks:
New here, hoping for some help. I need to remove background noise from a recording done using mics at high gain. I guess there was some "auto" gain control, so the background noise is boosted during quite parts in the recording. Any help would be appreciated, thanks.

I use the noise reduction tools in Wavepad;

http://www.nch.com.au/wavepad/index.html

In fact I use it for quite a few things, it's a very handy little piece of software.

I posted the following in the wrong forum before I read this topic. I wonder if the free version of Wavepad has noise reduction tools already or not and if it could help with my problem? Here is my original post:

I have some projects that have some not too good recorded vocals: the vocals themselves are fine but there is a bit too much noise. I searched for a solution but all I could really find is information about iZotope RX and Sound Forge, but I really don't have the money for that kind of software... specially since I probably don't need the software anymore after dealing with these projects.
 
The noise isn't the low hum you often get (I already got rid of that using EQ) or bakcground noises (doors slamming, kids yelling) but it's some sort of overall background 'wind'. Because this is of course impossible to explain in words and because you need detailed information to (maybe) offer a solution, I uploaded a VERY short clip in which you can hear what I mean:
 
http://soundcloud.com/jeroen-van-engelenhoven/test
 
Now I could of course simply use a gate and in some songs this will work out fine but there are some passages and even two complete songs where you almost only hear the voice and when you use a gate on the above sample, you can clearly hear the noise being cut off. That sounds awful... So it would be best if I could also get rid of the noise during the singing...!
 
I wonder:
 
1. Could iZotope or Sound Forge really solve this...?
 
2. Are there any other options that cost (a LOT) less? (EDIT That might be Wavepad...?)
 
3. I read the iZotope demo won't let you save things but Sound Forge only has a time limited? Could anyone confirm that and if so, does that demo have the Noise Reduction 2 option in it...? Maybe that could help me out on these projects.
 
Due to circumstances re-recording isn't an option, unfortunately, so I'll have to make the best with what I've got...
 
P.S. I know I could download the Sound Forge demo and give it a try (that's what demo's are for) but I like to keep my PC very (very!) clean and I don't like downloading and installing software that may leave stuff cluttered on my system... that's why I'd like to know a bit more first. Maybe that demo doesn't even include the Noise Reduction plugin...

END of original post.
 
EDIT
 
Gave Wavepad a try... (The free version does have the noise reduction option!). Here is a quick comparison of the vocal before and after the edit (very short clip).
 
http://soundcloud.com/jeroen-van-engelenhoven/result
 
I think the difference is rather impressive...! You can very clearly hear the noise in the first part, at the beginning but specially at the end, where it suddenly fades. Also during the singing itself you can hear it. The second part sounds a lot cleaner...! If not completely clean!
 
Because the vocal was already fixed a long way in Sonar (EQ, compression) I exported the vocal track with all the 'correctioning plugins' but without reverb. I then edited the track in Wavepad and imported it back into Sonar, now only enabling reverb and turning of EQ, compression. I did have to turn the volume of the track a bit down, but imho it sounds a lot better now.

Thanks for the offer, much appreciated, but I am quite satisfied with the result that Wavepad (free!) is giving me (see the edit of my last post), so I'll keep it at that! Other programs may be better (although I wonder how) but they all cost at least 350 dollars, so... that makes the choice rather easy.