Media edition is medioka, its not built as a user system but more as a entertainment system.
PCi express, if you eiditn analog to digital as you can use the 16X interface where as AGP only hits 8X so its twice as fast (not a fact) Only onetype on graphics helps editing, that is the physix cards. these are geared more towards CGI
Dell use older technology, so what ever board they are using it will be slower than current board from any place. dell use cut price board in there systems.
There are Four SATA ports which is the most that many computer can use on a single port (4) most modern boards will take 8 over two controllers but they are not linked. so your maximum is 4 drives per array.
Sata is totally differnt to cable select, as the config allows you to select the active drive, if its RAID 0 then that are part of a single drive and both active. Yes they need direct connections there is not dual connections like IDE ribbons.
Tigerdirect is fine, had lots of reports on there systems, no big issues as I recall, you can head over to hardwareanalyst.com which is a US site and many people have exsperience of tigerdirect.
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