Here's how I did it:

Still do the Text-to-Columns with SPACES as your Delimiter. Now, you may have 3 or 4 columns per name.

Let's say:

Column A has the full Name
Column C has the 1st split of the name
Column D has the 2nd split of the name
Column E has the 3rd split of the name
Column F has the 4th split of the name

For the First Name column (Column H), your formula should be:
=IF(F1="",D1,CONCATENATE(D1," ",E1))

For the Last Name column (Column I), you formula should be:
=IF(AND(G1="",F1=""),E1,IF(AND(G1="",F1<""),F1,CO NCATENATE(F1," ",G1)))

The following scenario for the Last Name column output may be incorrect:
1. Person has 3 first names
2. Person has a JR., SR., II, IV, etc
3. Name has a middle initial in the list.