Ignore the fanboyistic rubbish about PS3s not being able to play online games properly - it's absolute rubbish. There's really no difference.

However, getting back to the question, this sounds like a connection problem indeed. I get this quite a lot on certain Xbox Live games; mostly when a game is hosted by someone with an awful connection!

It's possible that this could be a game- or server-related issue; I know there have been some issues with multiple players on the PC version. But, it's entirely more likely to be either your and/or your friends' connections.

What ISP do you/they have. If we're talking AOL, Tiscali, BT, or any of those larger providers, I would bank on it (mostly because these people emply such awful tricks such as traffic streaming, etc).

I would suggest that if you consider online gaming a major thing, and you have issues with other games (voice chat dropping out/not being heard, laggy gaming, dropped connections), then change your provider! There are hundreds in the UK alone (assuming you live here) - just check on www.ispreview.co.uk.
I, personally, use a company called TitanADSL - I get a constant 6Mb speed with almost unlimited download for £20 a month. That's just one example - there are cheaper alternatives, because everybody's different.

Failing that, if it's not such a big thing (or you don't have control over the connection), then you'll either have to live with it, or you could Google for other user's problems on the forums.

Really hope this helps - I know how annoying it can be.