Sed advice needed

[Piers Kittel <debian@biased.org>]

Hello all,

I need to delete some words out of a large file containing  
information about packets I'm analysing.  I know I can use sed to do  
this, but haven't really used it before, so am a bit unsure of how to  
do it.  Two example lines are as of below:

"181","1324.014027","111.111.111.111","111.111.111.111","RTP","Payload t 
ype=ITU-T H.261, SSRC=2008229573, Seq=54520, Time=1725612773, Mark"
"185","1324.078941","111.111.111.111","111.111.111.111","RTP","Payload t 
ype=ITU-T H.261, SSRC=2008229573, Seq=54521, Time=1725616276"

I need to convert the above to the below:

"181","1324.014027","111.111.111.111","111.111.111.111","RTP","54520"
"185","1324.078941","111.111.111.111","111.111.111.111","RTP","54521"

What's the best way to do this?  I've been reading the man pages of  
sed, cut and awk but I can't quite figure out how to do this.  Any  
ideas?

Thanks very much for your time in advance!

Regards - Piers