I’ll take the last portion first…
There are books and articles on the subject of tuning XP (try a google search on “tuning XP”), but the basics are to open the Services applet under Control Panel -> Administrative Tools and examine every service to see if it’s necessary for your operation. Here are some examples:
Universal Plug & Play (NOT the same as Plug & Play) – this one generates network traffic. Given your described environment, it can go.
DHCP Client – If you have statically assigned IP addresses, then you don’t need it running.
IPSec Policy – If you don’t use IP Sec, then disable that
Telephony, Remote Access, others are all candidates for disabling IF they’re not being used.
Between this and a google search, this should help.
Now – as to the first item, the length of time to connect, there are some items you didn’t supply, so this is somewhat guesswork.
1) What protocols are you using on the network? These days it should only be TCP/IP.
2) Are you using an NT Domain controller? Or is this a workgroup?
3)If a domain, are all computers (including XP) members of the domain?
Just a few things to look at. Write back with more information.
Also – have you looked at the system event logs on both the server and the XP station? There may be a clue in there as well.