Your registry will be wiped when you fdisk. You may have to reinstal the programs on the big disk. You should consider re-sizing the partition on your 40gb HDD.
Link is for a source of Partition Magic. I got it of their eBay listing for £19.99 inc p&P. Read the reviews from a google search. I have found it an excellent tool. Await further comments from the forum members.
P.S I have no connection with the above company - I have recommended then previously because I found the service good.