I have read a lot online trying to get Win 7 and XP to network and had little success with any of them.
So i ignore it all,the set to work,set to private and all that shit and here is what works,simple and effective.
I have 2 Win 7 PCs and 4 XP PCs.
All the XP machines worked before 7 and are in Workgroup,so we leave them alone as 7 sees them,and logs into them any way.
In Win 7 use home group,set your Guest account with a Password as XP needed anyway,and turn off password protected file sharing.Give Guest account in XP one as well for more security of your network.
XP sees the homegroup computers, and all you need to log on from XP is Guest/Password and your in.
On XP look in my Network places, browse workgroup computers and there are your Win 7 PCs.
Takes 2 Mins to set up,but if you go the route you would think, by putting Win 7 in a work group XP cant log into it.And i tried all ways on that one.
You could create named accounts on the machine and use that as well ,it all depends on your setup or preference,as mine is a wired network it suits me.
Any better solutions let me Know
PS Ive read this again Sober and basically mean log in as a User on the7 machine from XP but will elaborate further if neccesary