802.3ad Link Aggregation between two hosts using crossover cables

I have two machines, one running Red Hat Fedora Core 2, the other
running Windows XP Pro. I happened to have some extra ethernet cards
lying about, and decided to play around with link aggregation (a.k.a.
channel bonding, port trunking, etc.). On the Linux side, I am using
the bonding module in mode 4 (802.3ad), and on the Windows side I have
NIC Express 4.0 installed and set for 802.3ad mode. The hosts are
connected via two crossover cables. I've played around quite a bit, but
haven't had much luck; at one point, I could ping from either host to
the other with either or both cables connected, but couldn't do
anything useful (SSH, HTTP) unless a particular card on the Windows box
was plugged into either of the cards on the Linux box.

Is what I'm trying to do even possible with 802.3ad? If not, is it
possible with another bonding mode? NIC Express supports a mode in
which load balancing is disabled, and FEC/GEC trunking as well as
802.3ad, and a proprietary mode. The reason I was doing this was for
the extra speed, but if that's not possible, I'd settle for just the
fault tolerance.

Some of the errors I've seen:

Linux:
- bonding: Warning: No 802.3ad response from the link partner for any
adapters in the bond

Windows:
- Group NIC Express Aggregate Link has one or more interfaces connected
to a switch that does not support 802.3ad trunking
- Group NIC Express Aggregate Link has a trunking mismatch
Thanks,

Gabe