IP help needed, Please!

First of all, what do you mean by allowing users access to the Internet? Do you mean as in logging on this system invidivually or setting up the system to allow connection sharing to more client machines?
If the latter, you can make a router out of that system you inherited using two network cards and a router OS such as IPCop, BrazilFW, or FloppyFW (a google search will get you to their sites).

* Wow, where'd you find that job? Was it on Monster.com? (laugh). Don't worry, you wouldn't be the first one that had to learn as they were going. I've done that a bunch of times myself.

Find out as much as you can about the network (boy would that be fun). Run "ipconfig" command (including "ipconfig /a" ) on machines on the network.

Make a note of things like:

DHCP SERVER

DEFAULT GATEWAY

DNS SERVERS

(Do you log onto a domain?) DOMAIN CONROLLER(S)?

* Find out where/what those boxes are? Are they routers? Are the computers acting as routers?

* Find out what is/are Internet Connection(s)

Is it DSL?
T1?
T3?

* Any Firewall(s)?

FIREWALLS?

**** Chances are machines were limited from Internet Access for reason(s) other than running out of IP Addresses. Although it is possible that they were allocated a small slice of IP space (e.g. a /28 and only 14 possible IP Addresses), typically NAT - Network Address Translation is being done on a router or server. With NAT you can have a lot more IP Addresses...

* Your 1XX doesn't make much sense without filling in more of the X's, your mention of 10. IP Addresses is most assuredly RFC-1918 Private IP Space. It could be kept completely private or it could be routed through NAT to Real IP Address space. Therein lies the trick to more computers being able to have Internet Access.