Tracing an email received from hotmail (attached headers)

[shabs]

Hello,
I was reading the posts in this forum but I have trouble finding out the IP from an email I sent myself from my hotmail account to my yahoo account (both web based). Here are the headers taken from yahoo:

Return-Path: <xxxx@hotmail.com>
Authentication-Results: mta376.mail.mud.yahoo.com from=hotmail.com; domainkeys=neutral (no sig)
Received: from 65.55.90.18 (EHLO snt0-omc1-s7.snt0.hotmail.com) (65.55.90.18) by mta376.mail.mud.yahoo.com with SMTP; Sat, 25 Apr 2009 15:00:23 -0700
Received: from SNT105-W32 ([65.55.90.9]) by snt0-omc1-s7.snt0.hotmail.com with Microsoft SMTPSVC(6.0.3790.3959); Sat, 25 Apr 2009 15:00:23 -0700
Message-ID: <SNT105-W32EA34095789D17FF870828E9A0@phx.gbl>
Return-Path: xxxx@hotmail.com
Content-Type: multipart/alternative; boundary="_f7584c52-6517-4bfd-9733-ace8fbbf967d_"
From:
xxxxx <xxxx@hotmail.com>

How would it be possible to determine the IP from this header?

Best Regards.