Have a few of those and the 2400 models (a bit cheaper) around the office for non-trading purposes. They have been very reliable.
One note - the 2400 does not offer much expansion capabilities (i.e. extra harddrives, memory, video cards, etc.) but it's perfect for email, MS Office type work.
If you want to do more intensive stuff, like photo/video editing, large spreadsheet calcs, etc. go with the 4600.
We've been very pleased with all of our Dell's.
John