Advice on which switch to buy

My company has 15-20 PCs hooked together with a Windows 2003 SBS based server. We have a Netgear JGS524 unmanaged switch right now. We are soon buying a new server and want to upgrade our switch at the same time to a 24 or more port managed gigabit switch possibly with a a few PoE ports. I was told that our current switch has a 2Mb packet buffer and may be the cause of occasional long waits for large file transfers. I was looking at a few different Netgear switches and saw that many newer presumably higher end switches have the same small buffer while some others have up to 16 Mb buffers. Can anyone tell me an appropriate model and/ or an appropriate buffer size for our small but heavily used network?