I already have something for myself that does what you ask. I have posted it below and you can use that with your sub calling.

[vba]
Public Sub saveAttachtoDisk(itm As Outlook.MailItem)
Dim objAtt As Outlook.Attachment
Dim saveFolder As String

For Each objAtt In itm.Attachments
If UCase(objAtt.DisplayName) Like "*.CSV" Then
saveFolder = "c:\temp"
ElseIf UCase(objAtt.DisplayName) Like "*.PDF" Then
saveFolder = "h:\temp"
Else
saveFolder = "c:\junk"
End If
Call downloadmail(itm, saveFolder)

Next
End Sub[/vba]
[vba]Sub downloadmail(myMailItem, strpath As String)
Dim strFileName As String
Dim strNewName As String
Dim strPre As String
Dim strExt As String
Dim myolAttachments As Attachments
Dim myolAtt As Attachment
Dim intExtlen As Integer
Dim w As Integer

Dim fs
Set fs = CreateObject("Scripting.FileSystemObject")

If myMailItem.Attachments.Count <> 0 Then
Set myolAttachments = myMailItem.Attachments
For Each myolAtt In myolAttachments
strFileName = myolAtt.DisplayName
'find out if the file exists in the download location already and if so rename
'to a filename including a number eg. file(1).xls
If fs.fileexists(strpath & "\" & strFileName) = True Then
strNewName = strFileName
'get the length of the extension including the .
intExtlen = Len(strFileName) - InStrRev(strFileName, ".") + 1
'check there is actually a file extension and if not set extension to blank
'and set strPre to the full file name
If InStrRev(strFileName, ".") > 0 Then
strExt = Right(strFileName, intExtlen)
strPre = Left(strFileName, Len(strFileName) - intExtlen)
Else
strExt = ""
strPre = strFileName
End If
'increase the file number (w) until the file name no longer exists file(1).ext to file(2).ext etc
'strpre = filename before extension strext = extension w=file number
While fs.fileexists(strpath & "\" & strNewName) = True
w = w + 1
strNewName = strPre & Chr(40) & w & Chr(41) & strExt
Wend
'set the new filename
strFileName = strNewName
w = 0
End If
myolAtt.SaveAsFile strpath & "\" & strFileName
AttachmentCount = AttachmentCount + 1
Set myolAtt = Nothing
Next
End If
myMailItem.UnRead = False
Set myolAttachments = Nothing
Set myMailItem = Nothing
End Sub
[/vba]

BTW this will also mark the email as read. Edit to your needs.