If you're concerned about long term support and service you could take a look at the Supplier Profiles here for Mesh and Dell
Mesh PCs seem to come top in the PC Advisor reviews, whereas Dell PCs are nowhere to be seen. This may indicate that Mesh go for high performance/price ratio, while Dell concentrate on customer service.
I'm happy with my Evesham Quest PC. Evesham pricing is competitive and the service was good when my PC had a problem after 11 months. They replaced the motherboard. It was a return to base warranty.