I use gmail with Imap for my iPhone, and another gmail account as backup spamfilter on my more spammed addresses (ie most of them), and it rocks.
If you're worried about the lack of professionalism implicit in a gmail address, buy yourself a domain with mailforwarding only (about £6 for 2 years) and have that forward to gmail. Thunderbird can do the rest, and only the cognoscenti will know you're using gmail.