What software to choose for remote newtwork client access?

[technochallenged]

I need bulletproof remote access for a new client to an existing small lan for a new branch location and for use at trade shows. We are running XP home on all locations; the lan is connected via Linksys router (4 computers); communication via DSL (T1 at trade shows); principle software is QuickBooks Pro used for sales & invoicing.

I don't know whether to try PC Anywhere, Dameware, UltraVCN or Remote Desktop.

Have tried Access Aywhere, but the delays are too long and frustrating, especially in a trade show retail environment.

Any suggections? As my handle implies I am ...