When you installed the new Harddrive, did you remove the IDE adapter connector from your old drive and install it on the new drive's 44 pin interface? Without it, your new Harddrive is not connected to the main board. The Fixed optical drive is slaved to the Harddrive on this model and it will not be recognized unless the harddrive is recognized. The new harddrive will be recognized by BIOS and DOS whether or not any prep has been done to it, but it will not be a bootable device until Windows has been run on it.
Inspiron 82001.4mhz Pentium IV1024mb PC2100 DDR SDRAM40gb Hitachi 7200rpm-HTE726040M9AT00-UDMA5Pioneer DVR-K05 DVD-RW in Fixed BayLS-120 SuperFloppy in ModularBayWindows XP Pro SP2I8kFanGui 2.20ATI Radeon 7500 64MB Video Card15" SXGA LCD