I prefer cisco and haven't used the Dell switches, although I know people who have. They say it's very similiar to cisco although the front end is a little bulkier..
I was with a group that did extensive testing on Dell switches, and even with the lower pricing they refused to use them over the Ciscos they had. There were several little issues, which I didn't understand as I'm not a network engineer, and then larger issues when they were put under high loads. This was over a year ago now though, things may have changed.
NEVER BUY DELL SWITCHES !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! !!!!!!!!!!!!!!!!!!!!!!
They just do NOT work.
We have had a customer with Dell PowerConnect switch. He was my nightmare. If power goes down for a reason, the switch forgets some of its settings (???!!!!), sudenlly without any reasons it stops working and has to rebooted. Stay away from it, for God sake!
But they are expensiver. If the guy is looking for a cheaper manageable switch, he can buy Dlink or HP Procurve. Both of them are very good at an affordable price.