What Should i Buy?

I currently have 20 client computers connected to a central server. I wish to upgrade the network (currently on 10/100 switches and a Dlink DFL-700 router) to make it go faster what would u guys suggest?

Do the workstations or the server have gigabit nics in them? If not, upgrading the networks speed may be quite a bit more costly than just replacing a switch
I'd go for either of these nics for the workstations:
Intel PWLA8391GT - $35
3com 3C2000-T - $47
And one of these for the server:
Intel PWLA8490MT - $99
3com 3C996B-T - $125

For just a 20 user network you dont really have to shell out for cisco (unless you have serious bucks, then go for it).
A 24 port netgear should be just fine. The NETGEAR JGS524FNA ($260) would probably fit your needs and it has two mini gbic slots for any future fiber expansion

<Gag!> Sorry. Wow.. I hope that was joke. A 3750 costs... well... a lot.

The main things I think you need to look for are at least a 24port (if not larger) 10/100 port switch that also has a couple of GigE ports. It's *really* important to look for a switch that's advertised as having a "non-blocking" architecture. What this means is that the switch-fabric/backplane of the switch has the same bandwidth as the sum of all it's ports. Basically... everybody can talk at the same time without any bottlenecks. Lesser/older switches don't have that feature.

So, like a 24+2 or a 48+2 switch will allow all your PC's to communicate at full throttle. You can even hook up the server via GigE to one of the GigE ports since that's a choke point for multiple users hitting it at once.

Tom's Networking just did a review on a decent NetGear switch that could fit the bill:
http://www.tomsnetworking.com/2006 [...] r_fs728ts/
NetGear also makes a 48port version.