Choosing 6.5 over 7 or 2000 is a big mistake. While support does still exist, it is going away soon. However, the real mistake is in the loss of processing power, support requirements once 6.5 is implemented, and preformance degredation when using 6.5.
One major difference between 6.5 and 7.0 was the way pages were handled within the database. On 6.5, you had a master page that pointed to another page that had pointers to other pages. To retrieve data SQL 6.5 had to jump all over the place just to get the data. With 7.0, there was a complete redesign of the layout and retrieval is based on a single page, therefore much quicker.
And with 6.5, you would NEVER run a Data Base Consistancy Check (DBCC) during operational hours and you do have to run DBCC regularly to keep all those pointers in line. With 7.0, because of the redesign, DBCC is very rarely ran, and it can be run during production hours because it no longer locks tables when running. I personally would not run it during production, but they say you can.
The back up time for SQL 6.5 databases is probably 3 to 5 times longer then 7.0 or 2K. Not to mention, with 7.0 and 2K you can now "detach" the database, make copies, and then reattach the database and have a complete backup without having the hassels of backing up the "master" database to keep everything in sync.
When it comes time for tuning, 6.5 requires an expert to fine tune all queries and hope they are running correctly. You can actually have 7.0 and 2K act with a self-tuning capability and improve preformance continually without an expert on staff. You may need the expert to address minor tweaking or adjustments, but the background tuning works really well.
You also get new datatypes that can handle larger values in SQL 7.0 and 2K. For instance, the varchar in 6.5 can only handle 255 characters while in 7.0 and 2K it can handle 4000 characters.
If you decide you want to have TEXT (memo in Access database) in your database, then get ready for another headache. Because of the pointer problem with 6.5, all TEXT is stored elsewhere and a pointer is stored in the database. In 7.0 and 2K, you can have data stored in place on the same page (which speeds up retrieval) up to a certain limit.
So what is the ROI if they go to 6.5 other than an initial license requirement savings, not much. Operations will be slower, maintenance will take longer, and recoveries will be more difficult if not possible at all after Microsoft drops support entirely. For the initial investment in a newer version of MS SQL you can be confident that preformance is outstanding, recovery complete, and maintenance a minimum. Extentions of the datatypes give you greater flexibility for growth and expansion as the business needs grow. If this were a one-time operation then I would say go for the 6.5, but if your business is about to depend on this database for corporate edge and future growth, then spend a little extra for the 7.0 or 2K and be sure you get what you need.
There is an adage: "You can pay me now, or really PAY me later." I think the adage applies here.
I hope this helps.
