How did you reformat it? If you use the tools available with win2k install, you should see available used & free disk space while selecting where to install.
What does POST screen show as disk size? (Is it set to auto detect in bios?)
If win2k is up and running, what does disk management (run diskmgmt.msc) tell you? If it shows a 4GB partition and 4GB free space, you can either just create a second partition, or if you have Partition Magic you can merge the partitions into one. Or you could reinstall win2k - removing existing and creating one 8GB partition with the install partitioning tools.
If disk managem