Hello Dennis,
how much money do you have to spend :) ?
The Cisco Catalyst 3750G-48TS switches have 48 Ethernet 10/100/1000 ports (and 4 SFP ports), but they are quite expensive (something in the are of $8,000). The advantage is that they have Gigabit ports, which gives you room for future growth.
A cheaper alternative would be the Cisco Catalyst 2950T 48 SI Switch, which cost around $1,700.
As for the IP Helper command, your IOS version should support it (I think it has been around a very long time, since IOS 10).
HTH,
GP