"This is usually 0x0000:0x7c00 (CS = 0, offset address 0x7c00). However, some BIOSes load to 0x7c0:0x0000 (CS = 0x07c0, offset address 0) -- which resolves to the same physical address, but can cause problems."

Don't rely on the BIOS' values. You can for example use a far jump to reset CS:IP if you rely on them having specific values.

[Edit: Or, maybe better, just don't rely on them.]