For the highest resolution output, it would have been better to use a bitmap file, rather than a jpeg, for the logo.
To get the best quality output, use Adobe's online file conversion service:
http://createpdf.adobe.com/
See here for the optimization settings available:
http://createpdf.adob...lp_cpdf?BP=&LOC=en_US
There's a very limited free trial available (just 5 documents), but a one month subscription (£5.55 + VAT = £7.20) won't break the bank anyway:
http://tinyurl.com/699ka2g
Chris