Best Instant Messaging for a company

I've been requested to look into an Instant Messaging system for our office.  I'd like some opinions from the Experts.  Money is a big consideration so it must be cheap.
J.R. SitmanIT DirectorAsked:
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Microsoft Office Communication Server 2007 R2 Standard, if you want it on premise.

If you are looking out for a cheaper alternative, you can try microsoft online services with the latest lync server in the package with free 24/7 support.. I guess it amounts to $10 a user per month.
Can you provide more details?
# of users?
are you only concerned with IM?  Do you need to be able to collaborate (share documents, etc)?
A free product that looked good when I reviewed it (if IM and audio/video capabilities are all you require):
This is a freeware product.
J.R. SitmanIT DirectorAuthor Commented:
58 total users, but all won't need the IM.  Don't need any feature except IM.  

I'll look at your link and post later.
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Go open-source! Use spark messenger and at the server out openfire. It can even integrate with msn accounts, log conversations, block contacts and much more!
Try this -
Very easy and flexible + special business features..
I would suggest MS communicator.
I can suggest LAN messenger
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J.R. SitmanIT DirectorAuthor Commented:
I'll check the suggestions out and post later.

hi all
skype is nice too.
instant conversation, desktop sharing, voice and video
J.R. SitmanIT DirectorAuthor Commented:
I forgot about Skype.  Can that be used free at a business?
Jump to for business solution
Otherwise, as individual, I guess you are able to use skype
PS: in my company, we are using Microsoft Office communicator (7000 employees around the world)
Yes u can use skype, go through the attached doc to see how u can confgure skype for business in  a secured way.
J.R. SitmanIT DirectorAuthor Commented:
These two choices are best for our budget.

Thanks to all.
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