WIN7 & XP network access

I have WIN7 64 bit computer and a WIN XP 32 bit computer I wish to share files between. The WIN7 comp used to be have WIN XP on it and I did have a successful Ethernet connection between the two machines.
Problems:
I have status connected (on WIN XP) but no network connection (on WIN7).
I have tried (I think) just about every bit of advice I can read about on network set-up but something is just not working. I have even tried manual configuration of the IP address under TCP/IPv4 to the same address that worked under WIN XP (I had a manual setting under XP).
I have turned off all firewalls and set all sharing to yes etc.
My set-up is like this: WIN XP comp connects to internet and I disable this connection to connect this comp to the WIN7 comp for networking. I dont want internet connection for the WIN7 comp to ensure cleanliness as its my work computer.
Unfortunately all the how-to's for networking are too simple for my problem it seems.
Does anyone have any suggestions. Thanks in advance.

When both comps were using WIN XP then there was file sharing. Presently the problem is I have a "connected" XP comp and a "no network access" WIN7 comp.
I was told you can only have one network enabled at any one time per computer. Hence I normally disable the internet connection before enabling the network to the 2nd comp. This allowed me to use my one jack router connecting to the internet. I would then disable internet and enable the network to send my work compter any files I might have downloaded. Does bridging allow two networks to function simultaneously?

I tried the link you suggested about cross over cable.
It all makes sense but I get these addresses when I ipconfig/all:
WIN XP IP 169.254.150.164 mask 255.255.0.0 there is no gateway or any other address.
WIN 7 IP 169. 254.135.204 mask 255.255.0.0 nothing else.
I don't get any connection when using my listed settings or the tuts listed settings either. What do you suggest i do next.

My wired router has only one port, yes. I am quite happy to have the WIN XP machine as my internet (dirty) browser and my WIN7 as my work photoshop comp, without internet connection (safer security).

I have tried manual input and auto obtain ip address, I tried the tuts numbers all to no avail.
Let me tell you the Internet address on my WIN XP comp and perhaps you can give me the address I should be using on my WINXP network connection and associated WIN7 network connection addresses that will work when manually inputed.
I use a 1 port Belkin modem manually configured to the internet as instructed by the Belkin service staff with these addresses:
IP 10.1.1.2
Subnet 255.0.0.0
default gateway 10.1.1.1
DSN server 10.1.1.1

Before WIN7 I successfully had internet and network connection using WIN XP to WIN XP computers.
Here are my adresses that previously worked:
Computer A WINXP
Internet Connection
IP 10.1.1.2 SN 255.0.0.0 DG 10.1.1.1 DNS 10.1.1.1
LAN Connection
IP 10.1.1.9
Computer B WINXP
LAN Connection
IP 10.1.1.5

I just changed Computer B over to WIN7 and using IP 10.1.1.5 doesn't work now.

Ok I tried your numbers above:
Comp A
Internet Connection disabled
IP 10.1.1.2
Subnet 255.0.0.0
default gateway 10.1.1.1
DSN server 10.1.1.1

Comp A
Lan Connection enabled says its connected
IP 10.1.1.2
Subnet 255.0.0.0
default gateway 10.1.1.1
DSN server 10.1.1.1


Comp B
LAN Connection enabled says no network access
IP 10.1.1.4
Subnet 255.0.0.0
default gateway 10.1.1.1
DSN server 10.1.1.1

Ping times out and no connection
Thank you for your input, what do you suggest next.