Re-aging through a collection agency

I had a credit card through Citibank VISA that was passed off to a collection agency. I recently started to pay it off (through the CA) in September at $50/month...which they gladly accepted. Now I'm thinking I may have made a mistake after reading other information here about letting some accounts just fall off instead of paying them.

The deal is...the original creditor is not listed on my report any longer...must be because it's past 7 years old. The CA listing is the only one there...and they list the "Date major delinquency first reported" as 1/07...which is probably when they purchased the account. Here is what the listing looks like on my report:

UNIFUND
Hide Details VERIZ-2398
015258XXXX N/A $1,210 11/2007 $1,210 COLLECTION ACCOUNT $0
UNIFUND10625 Techwood Cir
Cincinnati, OH-452422846
(888) 384-8134

Account Number: VERIZ-2398015258XXXX Current Status: COLLECTION ACCOUNT
Account Owner: Individual Account.
High Credit: $602
Type of Account : Open
Credit Limit: $0
Term Duration:
Terms Frequency:
Date Opened:
Balance: $1,210
Date Reported: 11/2007
Amount Past Due: $1,210
Date of Last Payment: 10/2007
Actual Payment Amount: $0
Scheduled Payment Amount: $0
Date of Last Activity: 01/2002
Date Major Delinquency First Reported: 01/2007 Months Reviewed: 7
Creditor Classification:
Activity Description: N/A
Charge Off Amount: $0
Deferred Payment Start Date:
Balloon Payment Amount: $0
Balloon Payment Date:
Date Closed:
Type of Loan: Factoring Company Account (debt purchaser)

Comments: Collection account

81-Month Payment History
No 81-Month Payment Data available for display.

What do you make of this one? Is there any way I can dispute this as not being valid or did I screw it up by paying them? How can I fix it if I did make a mess?

Thanks!