Normally, installing Debian on Dell servers is piece of cake. This particular 1950 came with Broadcom NICs and PERC5 controller. Debian 5.0.4 does not include driver for Broadcom drivers due to some copyright restrictions. However, the driver is available as deb package. Download it and copy to FAT or FAT32 formatted USB drive. When prompted for NIC driver during the installation process, insert USB drive into USB port. As soon as server loads the driver and moves to the next screen in installation process, remove the drive. If you do not remove the USB drive before installation process gets to partitioning, your drive sequence will we out of whack. You'll have to boot from CD and edit /etc/fstab.
Since this server has hardware I wanted to use instead of configuring software RAID in Linux. The question is how to monitor RAID state from Debian. There is no deb package or source code, but LSI provides RPM. I downloaded "MegaCLI - Linux" from "Miscellaneous" section, unpacked it, installed "alien" on Debian (sudo apt-get install aliean) and then "sudo alien -i MegaCli-1.01-0.i386.rpm". It install MegaCli under /opt/MegaRAID/MegaCli. Moritz Mertinkat has great emergency cheat sheet for MegaCli usage.